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Post-installation configuration

OpenShift Container Platform 4.12

Day 2 operations for OpenShift Container Platform

Red Hat OpenShift Documentation Team

Abstract

This document provides instructions and guidance on post installation activities for OpenShift Container Platform.

Chapter 1. Postinstallation configuration overview

After installing OpenShift Container Platform, a cluster administrator can configure and customize the following components:

  • Machine
  • Bare metal
  • Cluster
  • Node
  • Network
  • Storage
  • Users
  • Alerts and notifications

1.1. Post-installation configuration tasks

You can perform the post-installation configuration tasks to configure your environment to meet your need.

The following lists details these configurations:

  • Configure operating system features: The Machine Config Operator (MCO) manages MachineConfig objects. By using the MCO, you can configure nodes and custom resources.

  • Configure bare metal nodes: You can use the Bare Metal Operator (BMO) to manage bare metal hosts. The BMO can complete the following operations:

    • Inspects hardware details of the host and report them to the bare metal host.
    • Inspect firmware and configure BIOS settings.
    • Provision hosts with a desired image.
    • Clean disk contents for the host before or after provisioning the host.

  • Configure cluster features. You can modify the following features of an OpenShift Container Platform cluster:

    • Image registry
    • Networking configuration
    • Image build behavior
    • Identity provider
    • The etcd configuration
    • Machine set creation to handle the workloads
    • Cloud provider credential management

  • Configuring a private cluster: By default, the installation program provisions OpenShift Container Platform by using a publicly accessible DNS and endpoints. To make your cluster accessible only from within an internal network, configure the following components to make them private:

    • DNS
    • Ingress Controller
    • API server

  • Perform node operations: By default, OpenShift Container Platform uses Red Hat Enterprise Linux CoreOS (RHCOS) compute machines. You can perform the following node operations:

    • Add and remove compute machines.
    • Add and remove taints and tolerations.
    • Configure the maximum number of pods per node.
    • Enable Device Manager.
  • Configure users: OAuth access tokens allow users to authenticate themselves to the API. You can configure OAuth to perform the following tasks:
  • Specify an identity provider
  • Use role-based access control to define and supply permissions to users
  • Install an Operator from OperatorHub
  • Configuring alert notifications: By default, firing alerts are displayed on the Alerting UI of the web console. You can also configure OpenShift Container Platform to send alert notifications to external systems.

Chapter 2. Configuring a private cluster

After you install an OpenShift Container Platform version 4.12 cluster, you can set some of its core components to be private.

2.1. About private clusters

By default, OpenShift Container Platform is provisioned using publicly-accessible DNS and endpoints. You can set the DNS, Ingress Controller, and API server to private after you deploy your private cluster.

Important

If the cluster has any public subnets, load balancer services created by administrators might be publicly accessible. To ensure cluster security, verify that these services are explicitly annotated as private.

DNS

If you install OpenShift Container Platform on installer-provisioned infrastructure, the installation program creates records in a pre-existing public zone and, where possible, creates a private zone for the cluster’s own DNS resolution. In both the public zone and the private zone, the installation program or cluster creates DNS entries for *.apps, for the Ingress object, and api, for the API server.

The *.apps records in the public and private zone are identical, so when you delete the public zone, the private zone seamlessly provides all DNS resolution for the cluster.

Ingress Controller

Because the default Ingress object is created as public, the load balancer is internet-facing and in the public subnets.

The Ingress Operator generates a default certificate for an Ingress Controller to serve as a placeholder until you configure a custom default certificate. Do not use Operator-generated default certificates in production clusters. The Ingress Operator does not rotate its own signing certificate or the default certificates that it generates. Operator-generated default certificates are intended as placeholders for custom default certificates that you configure.

API server

By default, the installation program creates appropriate network load balancers for the API server to use for both internal and external traffic.

On Amazon Web Services (AWS), separate public and private load balancers are created. The load balancers are identical except that an additional port is available on the internal one for use within the cluster. Although the installation program automatically creates or destroys the load balancer based on API server requirements, the cluster does not manage or maintain them. As long as you preserve the cluster’s access to the API server, you can manually modify or move the load balancers. For the public load balancer, port 6443 is open and the health check is configured for HTTPS against the /readyz path.

On Google Cloud Platform, a single load balancer is created to manage both internal and external API traffic, so you do not need to modify the load balancer.

On Microsoft Azure, both public and private load balancers are created. However, because of limitations in current implementation, you just retain both load balancers in a private cluster.

2.2. Configuring DNS records to be published in a private zone

For all OpenShift Container Platform clusters, whether public or private, DNS records are published in a public zone by default.

You can remove the public zone from the cluster DNS configuration to avoid exposing DNS records to the public. You might want to avoid exposing sensitive information, such as internal domain names, internal IP addresses, or the number of clusters at an organization, or you might simply have no need to publish records publicly. If all the clients that should be able to connect to services within the cluster use a private DNS service that has the DNS records from the private zone, then there is no need to have a public DNS record for the cluster.

After you deploy a cluster, you can modify its DNS to use only a private zone by modifying the DNS custom resource (CR). Modifying the DNS CR in this way means that any DNS records that are subsequently created are not published to public DNS servers, which keeps knowledge of the DNS records isolated to internal users. This can be done when you configure the cluster to be private, or if you never want DNS records to be publicly resolvable.

Alternatively, even in a private cluster, you might keep the public zone for DNS records because it allows clients to resolve DNS names for applications running on that cluster. For example, an organization can have machines that connect to the public internet and then establish VPN connections for certain private IP ranges in order to connect to private IP addresses. The DNS lookups from these machines use the public DNS to determine the private addresses of those services, and then connect to the private addresses over the VPN.

Procedure

  1. Review the DNS CR for your cluster by running the following command and observing the output: 

    $ oc get dnses.config.openshift.io/cluster -o yaml

    Example output

    apiVersion: config.openshift.io/v1
kind: DNS
metadata:
  creationTimestamp: "2019-10-25T18:27:09Z"
  generation: 2
  name: cluster
  resourceVersion: "37966"
  selfLink: /apis/config.openshift.io/v1/dnses/cluster
  uid: 0e714746-f755-11f9-9cb1-02ff55d8f976
spec:
  baseDomain: <base_domain>
  privateZone:
    tags:
      Name: <infrastructure_id>-int
      kubernetes.io/cluster/<infrastructure_id>: owned
  publicZone:
    id: Z2XXXXXXXXXXA4
status: {}

    Note that the spec section contains both a private and a public zone.

  2. Patch the DNS CR to remove the public zone by running the following command: 

    $ oc patch dnses.config.openshift.io/cluster --type=merge --patch='{"spec": {"publicZone": null}}'

    Example output

    dns.config.openshift.io/cluster patched

    The Ingress Operator consults the DNS CR definition when it creates DNS records for IngressController objects. If only private zones are specified, only private records are created.

    Important

    Existing DNS records are not modified when you remove the public zone. You must manually delete previously published public DNS records if you no longer want them to be published publicly.

Verification

  • Review the DNS CR for your cluster and confirm that the public zone was removed, by running the following command and observing the output: 

    $ oc get dnses.config.openshift.io/cluster -o yaml

    Example output

    apiVersion: config.openshift.io/v1
kind: DNS
metadata:
  creationTimestamp: "2019-10-25T18:27:09Z"
  generation: 2
  name: cluster
  resourceVersion: "37966"
  selfLink: /apis/config.openshift.io/v1/dnses/cluster
  uid: 0e714746-f755-11f9-9cb1-02ff55d8f976
spec:
  baseDomain: <base_domain>
  privateZone:
    tags:
      Name: <infrastructure_id>-int
      kubernetes.io/cluster/<infrastructure_id>-wfpg4: owned
status: {}

2.3. Setting the Ingress Controller to private

After you deploy a cluster, you can modify its Ingress Controller to use only a private zone.

Procedure

  1. Modify the default Ingress Controller to use only an internal endpoint: 

    $ oc replace --force --wait --filename - <<EOF
apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  namespace: openshift-ingress-operator
  name: default
spec:
  endpointPublishingStrategy:
    type: LoadBalancerService
    loadBalancer:
      scope: Internal
EOF

    Example output

    ingresscontroller.operator.openshift.io "default" deleted
ingresscontroller.operator.openshift.io/default replaced

    The public DNS entry is removed, and the private zone entry is updated.

2.4. Restricting the API server to private

After you deploy a cluster to Amazon Web Services (AWS) or Microsoft Azure, you can reconfigure the API server to use only the private zone.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Have access to the web console as a user with admin privileges.

Procedure

  1. In the web portal or console for your cloud provider, take the following actions:

    1. Locate and delete the appropriate load balancer component:

      • For AWS, delete the external load balancer. The API DNS entry in the private zone already points to the internal load balancer, which uses an identical configuration, so you do not need to modify the internal load balancer.
      • For Azure, delete the api-internal rule for the load balancer.
    2. Delete the api.$clustername.$yourdomain DNS entry in the public zone.

  2. Remove the external load balancers:

    Important

    You can run the following steps only for an installer-provisioned infrastructure (IPI) cluster. For a user-provisioned infrastructure (UPI) cluster, you must manually remove or disable the external load balancers.

    • If your cluster uses a control plane machine set, delete the following lines in the control plane machine set custom resource: 

      providerSpec:
  value:
    loadBalancers:
    - name: lk4pj-ext 1
      type: network 2
    - name: lk4pj-int
      type: network
      1 2
      Delete this line.

    • If your cluster does not use a control plane machine set, you must delete the external load balancers from each control plane machine.

      1. From your terminal, list the cluster machines by running the following command: 

        $ oc get machine -n openshift-machine-api

        Example output

        NAME                            STATE     TYPE        REGION      ZONE         AGE
lk4pj-master-0                  running   m4.xlarge   us-east-1   us-east-1a   17m
lk4pj-master-1                  running   m4.xlarge   us-east-1   us-east-1b   17m
lk4pj-master-2                  running   m4.xlarge   us-east-1   us-east-1a   17m
lk4pj-worker-us-east-1a-5fzfj   running   m4.xlarge   us-east-1   us-east-1a   15m
lk4pj-worker-us-east-1a-vbghs   running   m4.xlarge   us-east-1   us-east-1a   15m
lk4pj-worker-us-east-1b-zgpzg   running   m4.xlarge   us-east-1   us-east-1b   15m

        The control plane machines contain master in the name.

      2. Remove the external load balancer from each control plane machine:

        1. Edit a control plane machine object to by running the following command: 

          $ oc edit machines -n openshift-machine-api <control_plane_name> 1
          1
          Specify the name of the control plane machine object to modify.

        2. Remove the lines that describe the external load balancer, which are marked in the following example: 

          providerSpec:
  value:
    loadBalancers:
    - name: lk4pj-ext 1
      type: network 2
    - name: lk4pj-int
      type: network
          1 2
          Delete this line.
        3. Save your changes and exit the object specification.
        4. Repeat this process for each of the control plane machines.

Additional resources

Chapter 3. Bare metal configuration

When deploying OpenShift Container Platform on bare metal hosts, there are times when you need to make changes to the host either before or after provisioning. This can include inspecting the host’s hardware, firmware, and firmware details. It can also include formatting disks or changing modifiable firmware settings.

3.1. About the Bare Metal Operator

Use the Bare Metal Operator (BMO) to provision, manage, and inspect bare-metal hosts in your cluster.

The BMO uses three resources to complete these tasks:

  • BareMetalHost
  • HostFirmwareSettings
  • FirmwareSchema

The BMO maintains an inventory of the physical hosts in the cluster by mapping each bare-metal host to an instance of the BareMetalHost custom resource definition. Each BareMetalHost resource features hardware, software, and firmware details. The BMO continually inspects the bare-metal hosts in the cluster to ensure each BareMetalHost resource accurately details the components of the corresponding host.

The BMO also uses the HostFirmwareSettings resource and the FirmwareSchema resource to detail firmware specifications for the bare-metal host.

The BMO interfaces with bare-metal hosts in the cluster by using the Ironic API service. The Ironic service uses the Baseboard Management Controller (BMC) on the host to interface with the machine.

Some common tasks you can complete by using the BMO include the following:

  • Provision bare-metal hosts to the cluster with a specific image
  • Format a host’s disk contents before provisioning or after deprovisioning
  • Turn on or off a host
  • Change firmware settings
  • View the host’s hardware details

3.1.1. Bare Metal Operator architecture

The Bare Metal Operator (BMO) uses three resources to provision, manage, and inspect bare-metal hosts in your cluster. The following diagram illustrates the architecture of these resources:

BMO architecture overview

BareMetalHost

The BareMetalHost resource defines a physical host and its properties. When you provision a bare-metal host to the cluster, you must define a BareMetalHost resource for that host. For ongoing management of the host, you can inspect the information in the BareMetalHost or update this information.

The BareMetalHost resource features provisioning information such as the following:

  • Deployment specifications such as the operating system boot image or the custom RAM disk
  • Provisioning state
  • Baseboard Management Controller (BMC) address
  • Desired power state

The BareMetalHost resource features hardware information such as the following:

  • Number of CPUs
  • MAC address of a NIC
  • Size of the host’s storage device
  • Current power state

HostFirmwareSettings

You can use the HostFirmwareSettings resource to retrieve and manage the firmware settings for a host. When a host moves to the Available state, the Ironic service reads the host’s firmware settings and creates the HostFirmwareSettings resource. There is a one-to-one mapping between the BareMetalHost resource and the HostFirmwareSettings resource.

You can use the HostFirmwareSettings resource to inspect the firmware specifications for a host or to update a host’s firmware specifications.

Note

You must adhere to the schema specific to the vendor firmware when you edit the spec field of the HostFirmwareSettings resource. This schema is defined in the read-only FirmwareSchema resource.

FirmwareSchema

Firmware settings vary among hardware vendors and host models. A FirmwareSchema resource is a read-only resource that contains the types and limits for each firmware setting on each host model. The data comes directly from the BMC by using the Ironic service. The FirmwareSchema resource enables you to identify valid values you can specify in the spec field of the HostFirmwareSettings resource.

A FirmwareSchema resource can apply to many BareMetalHost resources if the schema is the same.

Additional resources

3.2. About the BareMetalHost resource

Metal3 introduces the concept of the BareMetalHost resource, which defines a physical host and its properties. The BareMetalHost resource contains two sections:

  1. The BareMetalHost spec
  2. The BareMetalHost status

3.2.1. The BareMetalHost spec

The spec section of the BareMetalHost resource defines the desired state of the host.

Table 3.1. BareMetalHost spec
ParametersDescription

automatedCleaningMode

An interface to enable or disable automated cleaning during provisioning and de-provisioning. When set to disabled, it skips automated cleaning. When set to metadata, automated cleaning is enabled. The default setting is metadata. 

bmc:
  address:
  credentialsName:
  disableCertificateVerification:

The bmc configuration setting contains the connection information for the baseboard management controller (BMC) on the host. The fields are:

  • address: The URL for communicating with the host’s BMC controller.
  • credentialsName: A reference to a secret containing the username and password for the BMC.
  • disableCertificateVerification: A boolean to skip certificate validation when set to true.

bootMACAddress

The MAC address of the NIC used for provisioning the host.

bootMode

The boot mode of the host. It defaults to UEFI, but it can also be set to legacy for BIOS boot, or UEFISecureBoot.

consumerRef

A reference to another resource that is using the host. It could be empty if another resource is not currently using the host. For example, a Machine resource might use the host when the machine-api is using the host.

description

A human-provided string to help identify the host.

externallyProvisioned

A boolean indicating whether the host provisioning and deprovisioning are managed externally. When set:

  • Power status can still be managed using the online field.
  • Hardware inventory will be monitored, but no provisioning or deprovisioning operations are performed on the host.

firmware

Contains information about the BIOS configuration of bare metal hosts. Currently, firmware is only supported by iRMC, iDRAC, iLO4 and iLO5 BMCs. The sub fields are:

  • simultaneousMultithreadingEnabled: Allows a single physical processor core to appear as several logical processors. Valid settings are true or false.
  • sriovEnabled: SR-IOV support enables a hypervisor to create virtual instances of a PCI-express device, potentially increasing performance. Valid settings are true or false.
  • virtualizationEnabled: Supports the virtualization of platform hardware. Valid settings are true or false. 
image:
  url:
  checksum:
  checksumType:
  format:

The image configuration setting holds the details for the image to be deployed on the host. Ironic requires the image fields. However, when the externallyProvisioned configuration setting is set to true and the external management doesn’t require power control, the fields can be empty. The fields are:

  • url: The URL of an image to deploy to the host.
  • checksum: The actual checksum or a URL to a file containing the checksum for the image at image.url.
  • checksumType: You can specify checksum algorithms. Currently image.checksumType only supports md5, sha256, and sha512. The default checksum type is md5.
  • format: This is the disk format of the image. It can be one of raw, qcow2, vdi, vmdk, live-iso or be left unset. Setting it to raw enables raw image streaming in the Ironic agent for that image. Setting it to live-iso enables iso images to live boot without deploying to disk, and it ignores the checksum fields.

networkData

A reference to the secret containing the network configuration data and its namespace, so that it can be attached to the host before the host boots to set up the network.

online

A boolean indicating whether the host should be powered on (true) or off (false). Changing this value will trigger a change in the power state of the physical host. 

raid:
  hardwareRAIDVolumes:
  softwareRAIDVolumes:

(Optional) Contains the information about the RAID configuration for bare metal hosts. If not specified, it retains the current configuration.

Note

OpenShift Container Platform 4.12 supports hardware RAID for BMCs using the iRMC protocol only. OpenShift Container Platform 4.12 does not support software RAID.

See the following configuration settings:

  • hardwareRAIDVolumes: Contains the list of logical drives for hardware RAID, and defines the desired volume configuration in the hardware RAID. If you don’t specify rootDeviceHints, the first volume is the root volume. The sub-fields are:

    • level: The RAID level for the logical drive. The following levels are supported: 0,1,2,5,6,1+0,5+0,6+0.
    • name: The name of the volume as a string. It should be unique within the server. If not specified, the volume name will be auto-generated.
    • numberOfPhysicalDisks: The number of physical drives as an integer to use for the logical drove. Defaults to the minimum number of disk drives required for the particular RAID level.
    • physicalDisks: The list of names of physical disk drives as a string. This is an optional field. If specified, the controller field must be specified too.
    • controller: (Optional) The name of the RAID controller as a string to use in the hardware RAID volume.
    • rotational: If set to true, it will only select rotational disk drives. If set to false, it will only select solid-state and NVMe drives. If not set, it selects any drive types, which is the default behavior.
    • sizeGibibytes: The size of the logical drive as an integer to create in GiB. If unspecified or set to 0, it will use the maximum capacity of physical drive for the logical drive.

  • softwareRAIDVolumes: OpenShift Container Platform 4.12 does not support software RAID. The following information is for reference only. This configuration contains the list of logical disks for software RAID. If you don’t specify rootDeviceHints, the first volume is the root volume. If you set HardwareRAIDVolumes, this item will be invalid. Software RAIDs will always be deleted. The number of created software RAID devices must be 1 or 2. If there is only one software RAID device, it must be RAID-1. If there are two RAID devices, the first device must be RAID-1, while the RAID level for the second device can be 0, 1, or 1+0. The first RAID device will be the deployment device. Therefore, enforcing RAID-1 reduces the risk of a non-booting node in case of a device failure. The softwareRAIDVolume field defines the desired configuration of the volume in the software RAID. The sub-fields are:

    • level: The RAID level for the logical drive. The following levels are supported: 0,1,1+0.
    • physicalDisks: A list of device hints. The number of items should be greater than or equal to 2.
    • sizeGibibytes: The size of the logical disk drive as an integer to be created in GiB. If unspecified or set to 0, it will use the maximum capacity of physical drive for logical drive.

You can set the hardwareRAIDVolume as an empty slice to clear the hardware RAID configuration. For example: 

spec:
   raid:
     hardwareRAIDVolume: []

If you receive an error message indicating that the driver does not support RAID, set the raid, hardwareRAIDVolumes or softwareRAIDVolumes to nil. You might need to ensure the host has a RAID controller. 

rootDeviceHints:
  deviceName:
  hctl:
  model:
  vendor:
  serialNumber:
  minSizeGigabytes:
  wwn:
  wwnWithExtension:
  wwnVendorExtension:
  rotational:

The rootDeviceHints parameter enables provisioning of the RHCOS image to a particular device. It examines the devices in the order it discovers them, and compares the discovered values with the hint values. It uses the first discovered device that matches the hint value. The configuration can combine multiple hints, but a device must match all hints to get selected. The fields are:

  • deviceName: A string containing a Linux device name like /dev/vda. The hint must match the actual value exactly.
  • hctl: A string containing a SCSI bus address like 0:0:0:0. The hint must match the actual value exactly.
  • model: A string containing a vendor-specific device identifier. The hint can be a substring of the actual value.
  • vendor: A string containing the name of the vendor or manufacturer of the device. The hint can be a sub-string of the actual value.
  • serialNumber: A string containing the device serial number. The hint must match the actual value exactly.
  • minSizeGigabytes: An integer representing the minimum size of the device in gigabytes.
  • wwn: A string containing the unique storage identifier. The hint must match the actual value exactly.
  • wwnWithExtension: A string containing the unique storage identifier with the vendor extension appended. The hint must match the actual value exactly.
  • wwnVendorExtension: A string containing the unique vendor storage identifier. The hint must match the actual value exactly.
  • rotational: A boolean indicating whether the device should be a rotating disk (true) or not (false).

3.2.2. The BareMetalHost status

The BareMetalHost status represents the host’s current state, and includes tested credentials, current hardware details, and other information.

Table 3.2. BareMetalHost status
ParametersDescription

goodCredentials

A reference to the secret and its namespace holding the last set of baseboard management controller (BMC) credentials the system was able to validate as working.

errorMessage

Details of the last error reported by the provisioning backend, if any.

errorType

Indicates the class of problem that has caused the host to enter an error state. The error types are:

  • provisioned registration error: Occurs when the controller is unable to re-register an already provisioned host.
  • registration error: Occurs when the controller is unable to connect to the host’s baseboard management controller.
  • inspection error: Occurs when an attempt to obtain hardware details from the host fails.
  • preparation error: Occurs when cleaning fails.
  • provisioning error: Occurs when the controller fails to provision or deprovision the host.
  • power management error: Occurs when the controller is unable to modify the power state of the host.
  • detach error: Occurs when the controller is unable to detatch the host from the provisioner. 
hardware:
  cpu
    arch:
    model:
    clockMegahertz:
    flags:
    count:

The hardware.cpu field details of the CPU(s) in the system. The fields include:

  • arch: The architecture of the CPU.
  • model: The CPU model as a string.
  • clockMegahertz: The speed in MHz of the CPU.
  • flags: The list of CPU flags. For example, 'mmx','sse','sse2','vmx' etc.
  • count: The number of CPUs available in the system. 
hardware:
  firmware:

Contains BIOS firmware information. For example, the hardware vendor and version. 

hardware:
  nics:
  - ip:
    name:
    mac:
    speedGbps:
    vlans:
    vlanId:
    pxe:

The hardware.nics field contains a list of network interfaces for the host. The fields include:

  • ip: The IP address of the NIC, if one was assigned when the discovery agent ran.
  • name: A string identifying the network device. For example, nic-1.
  • mac: The MAC address of the NIC.
  • speedGbps: The speed of the device in Gbps.
  • vlans: A list holding all the VLANs available for this NIC.
  • vlanId: The untagged VLAN ID.
  • pxe: Whether the NIC is able to boot using PXE. 
hardware:
  ramMebibytes:

The host’s amount of memory in Mebibytes (MiB). 

hardware:
  storage:
  - name:
    rotational:
    sizeBytes:
    serialNumber:

The hardware.storage field contains a list of storage devices available to the host. The fields include:

  • name: A string identifying the storage device. For example, disk 1 (boot).
  • rotational: Indicates whether the disk is rotational, and returns either true or false.
  • sizeBytes: The size of the storage device.
  • serialNumber: The device’s serial number. 
hardware:
  systemVendor:
    manufacturer:
    productName:
    serialNumber:

Contains information about the host’s manufacturer, the productName, and the serialNumber.

lastUpdated

The timestamp of the last time the status of the host was updated.

operationalStatus

The status of the server. The status is one of the following:

  • OK: Indicates all the details for the host are known, correctly configured, working, and manageable.
  • discovered: Implies some of the host’s details are either not working correctly or missing. For example, the BMC address is known but the login credentials are not.
  • error: Indicates the system found some sort of irrecoverable error. Refer to the errorMessage field in the status section for more details.
  • delayed: Indicates that provisioning is delayed to limit simultaneous provisioning of multiple hosts.
  • detached: Indicates the host is marked unmanaged.

poweredOn

Boolean indicating whether the host is powered on. 

provisioning:
  state:
  id:
  image:
  raid:
  firmware:
  rootDeviceHints:

The provisioning field contains values related to deploying an image to the host. The sub-fields include:

  • state: The current state of any ongoing provisioning operation. The states include:

    • <empty string>: There is no provisioning happening at the moment.
    • unmanaged: There is insufficient information available to register the host.
    • registering: The agent is checking the host’s BMC details.
    • match profile: The agent is comparing the discovered hardware details on the host against known profiles.
    • available: The host is available for provisioning. This state was previously known as ready.
    • preparing: The existing configuration will be removed, and the new configuration will be set on the host.
    • provisioning: The provisioner is writing an image to the host’s storage.
    • provisioned: The provisioner wrote an image to the host’s storage.
    • externally provisioned: Metal3 does not manage the image on the host.
    • deprovisioning: The provisioner is wiping the image from the host’s storage.
    • inspecting: The agent is collecting hardware details for the host.
    • deleting: The agent is deleting the from the cluster.
  • id: The unique identifier for the service in the underlying provisioning tool.
  • image: The image most recently provisioned to the host.
  • raid: The list of hardware or software RAID volumes recently set.
  • firmware: The BIOS configuration for the bare metal server.
  • rootDeviceHints: The root device selection instructions used for the most recent provisioning operation.

triedCredentials

A reference to the secret and its namespace holding the last set of BMC credentials that were sent to the provisioning backend.

3.3. Getting the BareMetalHost resource

The BareMetalHost resource contains the properties of a physical host. You must get the BareMetalHost resource for a physical host to review its properties.

Procedure

  1. Get the list of BareMetalHost resources: 

    $ oc get bmh -n openshift-machine-api -o yaml
    Note

    You can use baremetalhost as the long form of bmh with oc get command.

  2. Get the list of hosts: 

    $ oc get bmh -n openshift-machine-api

  3. Get the BareMetalHost resource for a specific host: 

    $ oc get bmh <host_name> -n openshift-machine-api -o yaml

    Where <host_name> is the name of the host.

    Example output

    apiVersion: metal3.io/v1alpha1
kind: BareMetalHost
metadata:
  creationTimestamp: "2022-06-16T10:48:33Z"
  finalizers:
  - baremetalhost.metal3.io
  generation: 2
  name: openshift-worker-0
  namespace: openshift-machine-api
  resourceVersion: "30099"
  uid: 1513ae9b-e092-409d-be1b-ad08edeb1271
spec:
  automatedCleaningMode: metadata
  bmc:
    address: redfish://10.46.61.19:443/redfish/v1/Systems/1
    credentialsName: openshift-worker-0-bmc-secret
    disableCertificateVerification: true
  bootMACAddress: 48:df:37:c7:f7:b0
  bootMode: UEFI
  consumerRef:
    apiVersion: machine.openshift.io/v1beta1
    kind: Machine
    name: ocp-edge-958fk-worker-0-nrfcg
    namespace: openshift-machine-api
  customDeploy:
    method: install_coreos
  online: true
  rootDeviceHints:
    deviceName: /dev/sda
  userData:
    name: worker-user-data-managed
    namespace: openshift-machine-api
status:
  errorCount: 0
  errorMessage: ""
  goodCredentials:
    credentials:
      name: openshift-worker-0-bmc-secret
      namespace: openshift-machine-api
    credentialsVersion: "16120"
  hardware:
    cpu:
      arch: x86_64
      clockMegahertz: 2300
      count: 64
      flags:
      - 3dnowprefetch
      - abm
      - acpi
      - adx
      - aes
      model: Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz
    firmware:
      bios:
        date: 10/26/2020
        vendor: HPE
        version: U30
    hostname: openshift-worker-0
    nics:
    - mac: 48:df:37:c7:f7:b3
      model: 0x8086 0x1572
      name: ens1f3
    ramMebibytes: 262144
    storage:
    - hctl: "0:0:0:0"
      model: VK000960GWTTB
      name: /dev/sda
      sizeBytes: 960197124096
      type: SSD
      vendor: ATA
    systemVendor:
      manufacturer: HPE
      productName: ProLiant DL380 Gen10 (868703-B21)
      serialNumber: CZ200606M3
  lastUpdated: "2022-06-16T11:41:42Z"
  operationalStatus: OK
  poweredOn: true
  provisioning:
    ID: 217baa14-cfcf-4196-b764-744e184a3413
    bootMode: UEFI
    customDeploy:
      method: install_coreos
    image:
      url: ""
    raid:
      hardwareRAIDVolumes: null
      softwareRAIDVolumes: []
    rootDeviceHints:
      deviceName: /dev/sda
    state: provisioned
  triedCredentials:
    credentials:
      name: openshift-worker-0-bmc-secret
      namespace: openshift-machine-api
    credentialsVersion: "16120"

3.4. About the HostFirmwareSettings resource

You can use the HostFirmwareSettings resource to retrieve and manage the BIOS settings for a host. When a host moves to the Available state, Ironic reads the host’s BIOS settings and creates the HostFirmwareSettings resource. The resource contains the complete BIOS configuration returned from the baseboard management controller (BMC). Whereas, the firmware field in the BareMetalHost resource returns three vendor-independent fields, the HostFirmwareSettings resource typically comprises many BIOS settings of vendor-specific fields per host.

The HostFirmwareSettings resource contains two sections:

  1. The HostFirmwareSettings spec.
  2. The HostFirmwareSettings status.

3.4.1. The HostFirmwareSettings spec

The spec section of the HostFirmwareSettings resource defines the desired state of the host’s BIOS, and it is empty by default. Ironic uses the settings in the spec.settings section to update the baseboard management controller (BMC) when the host is in the Preparing state. Use the FirmwareSchema resource to ensure that you do not send invalid name/value pairs to hosts. See "About the FirmwareSchema resource" for additional details.

Example

spec:
  settings:
    ProcTurboMode: Disabled1

1
In the foregoing example, the spec.settings section contains a name/value pair that will set the ProcTurboMode BIOS setting to Disabled.
Note

Integer parameters listed in the status section appear as strings. For example, "1". When setting integers in the spec.settings section, the values should be set as integers without quotes. For example, 1.

3.4.2. The HostFirmwareSettings status

The status represents the current state of the host’s BIOS.

Table 3.3. HostFirmwareSettings
ParametersDescription
status:
  conditions:
  - lastTransitionTime:
    message:
    observedGeneration:
    reason:
    status:
    type:

The conditions field contains a list of state changes. The sub-fields include:

  • lastTransitionTime: The last time the state changed.
  • message: A description of the state change.
  • observedGeneration: The current generation of the status. If metadata.generation and this field are not the same, the status.conditions might be out of date.
  • reason: The reason for the state change.
  • status: The status of the state change. The status can be True, False or Unknown.
  • type: The type of state change. The types are Valid and ChangeDetected. 
status:
  schema:
    name:
    namespace:
    lastUpdated:

The FirmwareSchema for the firmware settings. The fields include:

  • name: The name or unique identifier referencing the schema.
  • namespace: The namespace where the schema is stored.
  • lastUpdated: The last time the resource was updated. 
status:
  settings:

The settings field contains a list of name/value pairs of a host’s current BIOS settings.

3.5. Getting the HostFirmwareSettings resource

The HostFirmwareSettings resource contains the vendor-specific BIOS properties of a physical host. You must get the HostFirmwareSettings resource for a physical host to review its BIOS properties.

Procedure

  1. Get the detailed list of HostFirmwareSettings resources: 

    $ oc get hfs -n openshift-machine-api -o yaml
    Note

    You can use hostfirmwaresettings as the long form of hfs with the oc get command.

  2. Get the list of HostFirmwareSettings resources: 

    $ oc get hfs -n openshift-machine-api

  3. Get the HostFirmwareSettings resource for a particular host 

    $ oc get hfs <host_name> -n openshift-machine-api -o yaml

    Where <host_name> is the name of the host.

3.6. Editing the HostFirmwareSettings resource

You can edit the HostFirmwareSettings of provisioned hosts.

Important

You can only edit hosts when they are in the provisioned state, excluding read-only values. You cannot edit hosts in the externally provisioned state.

Procedure

  1. Get the list of HostFirmwareSettings resources: 

    $ oc get hfs -n openshift-machine-api

  2. Edit a host’s HostFirmwareSettings resource: 

    $ oc edit hfs <host_name> -n openshift-machine-api

    Where <host_name> is the name of a provisioned host. The HostFirmwareSettings resource will open in the default editor for your terminal.

  3. Add name/value pairs to the spec.settings section:

    Example

    spec:
  settings:
    name: value 1

    1
    Use the FirmwareSchema resource to identify the available settings for the host. You cannot set values that are read-only.
  4. Save the changes and exit the editor.

  5. Get the host’s machine name: 

     $ oc get bmh <host_name> -n openshift-machine name

    Where <host_name> is the name of the host. The machine name appears under the CONSUMER field.

  6. Annotate the machine to delete it from the machineset: 

    $ oc annotate machine <machine_name> machine.openshift.io/delete-machine=true -n openshift-machine-api

    Where <machine_name> is the name of the machine to delete.

  7. Get a list of nodes and count the number of worker nodes: 

    $ oc get nodes

  8. Get the machineset: 

    $ oc get machinesets -n openshift-machine-api

  9. Scale the machineset: 

    $ oc scale machineset <machineset_name> -n openshift-machine-api --replicas=<n-1>

    Where <machineset_name> is the name of the machineset and <n-1> is the decremented number of worker nodes.

  10. When the host enters the Available state, scale up the machineset to make the HostFirmwareSettings resource changes take effect: 

    $ oc scale machineset <machineset_name> -n openshift-machine-api --replicas=<n>

    Where <machineset_name> is the name of the machineset and <n> is the number of worker nodes.

3.7. Verifying the HostFirmware Settings resource is valid

When the user edits the spec.settings section to make a change to the HostFirmwareSetting(HFS) resource, the Bare Metal Operator (BMO) validates the change against the FimwareSchema resource, which is a read-only resource. If the setting is invalid, the BMO will set the Type value of the status.Condition setting to False and also generate an event and store it in the HFS resource. Use the following procedure to verify that the resource is valid.

Procedure

  1. Get a list of HostFirmwareSetting resources: 

    $ oc get hfs -n openshift-machine-api

  2. Verify that the HostFirmwareSettings resource for a particular host is valid: 

    $ oc describe hfs <host_name> -n openshift-machine-api

    Where <host_name> is the name of the host.

    Example output

    Events:
  Type    Reason            Age    From                                    Message
  ----    ------            ----   ----                                    -------
  Normal  ValidationFailed  2m49s  metal3-hostfirmwaresettings-controller  Invalid BIOS setting: Setting ProcTurboMode is invalid, unknown enumeration value - Foo

    Important

    If the response returns ValidationFailed, there is an error in the resource configuration and you must update the values to conform to the FirmwareSchema resource.

3.8. About the FirmwareSchema resource

BIOS settings vary among hardware vendors and host models. A FirmwareSchema resource is a read-only resource that contains the types and limits for each BIOS setting on each host model. The data comes directly from the BMC through Ironic. The FirmwareSchema enables you to identify valid values you can specify in the spec field of the HostFirmwareSettings resource. The FirmwareSchema resource has a unique identifier derived from its settings and limits. Identical host models use the same FirmwareSchema identifier. It is likely that multiple instances of HostFirmwareSettings use the same FirmwareSchema.

Table 3.4. FirmwareSchema specification
ParametersDescription
<BIOS_setting_name>
  attribute_type:
  allowable_values:
  lower_bound:
  upper_bound:
  min_length:
  max_length:
  read_only:
  unique:

The spec is a simple map consisting of the BIOS setting name and the limits of the setting. The fields include:

  • attribute_type: The type of setting. The supported types are:

    • Enumeration
    • Integer
    • String
    • Boolean
  • allowable_values: A list of allowable values when the attribute_type is Enumeration.
  • lower_bound: The lowest allowed value when attribute_type is Integer.
  • upper_bound: The highest allowed value when attribute_type is Integer.
  • min_length: The shortest string length that the value can have when attribute_type is String.
  • max_length: The longest string length that the value can have when attribute_type is String.
  • read_only: The setting is read only and cannot be modified.
  • unique: The setting is specific to this host.

3.9. Getting the FirmwareSchema resource

Each host model from each vendor has different BIOS settings. When editing the HostFirmwareSettings resource’s spec section, the name/value pairs you set must conform to that host’s firmware schema. To ensure you are setting valid name/value pairs, get the FirmwareSchema for the host and review it.

Procedure

  1. To get a list of FirmwareSchema resource instances, execute the following: 

    $ oc get firmwareschema -n openshift-machine-api

  2. To get a particular FirmwareSchema instance, execute: 

    $ oc get firmwareschema <instance_name> -n openshift-machine-api -o yaml

    Where <instance_name> is the name of the schema instance stated in the HostFirmwareSettings resource (see Table 3).

Chapter 4. Configuring multi-architecture compute machines on an OpenShift Container Platform cluster

An OpenShift Container Platform cluster with multi-architecture compute machines is a cluster that supports compute machines with different architectures. You can deploy a cluster with multi-architecture compute machines by creating an Azure installer-provisioned cluster using the multi-architecture installer binary. For Azure installation, see Installing a cluster on Azure with customizations.

Warning

The multi-architecture compute machines Technology Preview feature has limited usability with installing, upgrading, and running payloads.

The following procedures explain how to generate an ARM64 boot image and create an Azure compute machine set with the ARM64 boot image. This adds ARM64 compute nodes to your cluster and deploys the desired amount of ARM64 virtual machines (VM). This section also shows how to upgrade your existing cluster to a cluster that supports multi-architecture compute machines. Clusters with multi-architecture compute machines are only available on Azure installer-provisioned infrastructures with x86_64 control plane machines.

Important

OpenShift Container Platform clusters with multi-architecture compute machines on Azure installer-provisioned infrastructure installations is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

4.1. Creating an ARM64 boot image using the Azure image gallery

To configure your cluster with multi-architecture compute machines, you must create an ARM64 boot image and add it to your Azure compute machine set. The following procedure describes how to manually generate an ARM64 boot image.

Prerequisites

  • You installed the Azure CLI (az).
  • You created a single-architecture Azure installer-provisioned cluster with the multi-architecture installer binary.

Procedure

  1. Log in to your Azure account: 

    $ az login

  2. Create a storage account and upload the ARM64 virtual hard disk (VHD) to your storage account. The OpenShift Container Platform installation program creates a resource group, however, the boot image can also be uploaded to a custom named resource group: 

    $ az storage account create -n ${STORAGE_ACCOUNT_NAME} -g ${RESOURCE_GROUP} -l westus --sku Standard_LRS 1
    1
    The westus object is an example region.

  3. Create a storage container using the storage account you generated: 

    $ az storage container create -n ${CONTAINER_NAME} --account-name ${STORAGE_ACCOUNT_NAME}

  4. You must use the OpenShift Container Platform installation program JSON file to extract the URL and aarch64 VHD name:

    1. Extract the URL field and set it to RHCOS_VHD_ORIGIN_URL as the file name by running the following command: 

      $ RHCOS_VHD_ORIGIN_URL=$(oc -n openshift-machine-config-operator get configmap/coreos-bootimages -o jsonpath='{.data.stream}' | jq -r '.architectures.aarch64."rhel-coreos-extensions"."azure-disk".url')

    2. Extract the aarch64 VHD name and set it to BLOB_NAME as the file name by running the following command: 

      $ BLOB_NAME=rhcos-$(oc -n openshift-machine-config-operator get configmap/coreos-bootimages -o jsonpath='{.data.stream}' | jq -r '.architectures.aarch64."rhel-coreos-extensions"."azure-disk".release')-azure.aarch64.vhd

  5. Generate a shared access signature (SAS) token. Use this token to upload the RHCOS VHD to your storage container with the following commands: 

    $ end=`date -u -d "30 minutes" '+%Y-%m-%dT%H:%MZ'`
    $ sas=`az storage container generate-sas -n ${CONTAINER_NAME} --account-name ${STORAGE_ACCOUNT_NAME} --https-only --permissions dlrw --expiry $end -o tsv`

  6. Copy the RHCOS VHD into the storage container: 

    $ az storage blob copy start --account-name ${STORAGE_ACCOUNT_NAME} --sas-token "$sas" \
 --source-uri "${RHCOS_VHD_ORIGIN_URL}" \
 --destination-blob "${BLOB_NAME}" --destination-container ${CONTAINER_NAME}

    You can check the status of the copying process with the following command: 

    $ az storage blob show -c ${CONTAINER_NAME} -n ${BLOB_NAME} --account-name ${STORAGE_ACCOUNT_NAME} | jq .properties.copy

    Example output

    {
 "completionTime": null,
 "destinationSnapshot": null,
 "id": "1fd97630-03ca-489a-8c4e-cfe839c9627d",
 "incrementalCopy": null,
 "progress": "17179869696/17179869696",
 "source": "https://rhcos.blob.core.windows.net/imagebucket/rhcos-411.86.202207130959-0-azure.aarch64.vhd",
 "status": "success", 1
 "statusDescription": null
}

    1
    If the status parameter displays the success object, the copying process is complete.

  7. Create an image gallery using the following command: 

    $ az sig create --resource-group ${RESOURCE_GROUP} --gallery-name ${GALLERY_NAME}

    Use the image gallery to create an image definition. In the following example command, rhcos-arm64 is the name of the image definition. 

    $ az sig image-definition create --resource-group ${RESOURCE_GROUP} --gallery-name ${GALLERY_NAME} --gallery-image-definition rhcos-arm64 --publisher RedHat --offer arm --sku arm64 --os-type linux --architecture Arm64 --hyper-v-generation V2

  8. To get the URL of the VHD and set it to RHCOS_VHD_URL as the file name, run the following command: 

    $ RHCOS_VHD_URL=$(az storage blob url --account-name ${STORAGE_ACCOUNT_NAME} -c ${CONTAINER_NAME} -n "${BLOB_NAME}" -o tsv)

  9. Use the RHCOS_VHD_URL file, your storage account, resource group, and image gallery to create an image version. In the following example, 1.0.0 is the image version. 

    $ az sig image-version create --resource-group ${RESOURCE_GROUP} --gallery-name ${GALLERY_NAME} --gallery-image-definition rhcos-arm64 --gallery-image-version 1.0.0 --os-vhd-storage-account ${STORAGE_ACCOUNT_NAME} --os-vhd-uri ${RHCOS_VHD_URL}

  10. Your ARM64 boot image is now generated. You can access the ID of your image with the following command: 

    $ az sig image-version show -r $GALLERY_NAME -g $RESOURCE_GROUP -i rhcos-arm64 -e 1.0.0

    The following example image ID is used in the recourseID parameter of the compute machine set:

    Example resourceID

    /resourceGroups/${RESOURCE_GROUP}/providers/Microsoft.Compute/galleries/${GALLERY_NAME}/images/rhcos-arm64/versions/1.0.0

4.2. Adding a multi-architecture compute machine set to your cluster using the ARM64 boot image

To add ARM64 compute nodes to your cluster, you must create an Azure compute machine set that uses the ARM64 boot image. To create your own custom compute machine set on Azure, see "Creating a compute machine set on Azure".

Prerequisites

  • You installed the OpenShift CLI (oc).

Procedure

  • Create a machine set and modify the resourceID and vmSize parameters with the following command. This machine set will control the ARM64 worker nodes in your cluster: 
$ oc create -f arm64-machine-set-0.yaml

Sample YAML machine set with ARM64 boot image

+ 

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id>
    machine.openshift.io/cluster-api-machine-role: worker
    machine.openshift.io/cluster-api-machine-type: worker
  name: <infrastructure_id>-arm64-machine-set-0
  namespace: openshift-machine-api
spec:
  replicas: 2
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-arm64-machine-set-0
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
        machine.openshift.io/cluster-api-machine-role: worker
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-arm64-machine-set-0
    spec:
      lifecycleHooks: {}
      metadata: {}
      providerSpec:
        value:
          acceleratedNetworking: true
          apiVersion: machine.openshift.io/v1beta1
          credentialsSecret:
            name: azure-cloud-credentials
            namespace: openshift-machine-api
          image:
            offer: ""
            publisher: ""
            resourceID: /resourceGroups/${RESOURCE_GROUP}/providers/Microsoft.Compute/galleries/${GALLERY_NAME}/images/rhcos-arm64/versions/1.0.0 1
            sku: ""
            version: ""
          kind: AzureMachineProviderSpec
          location: <region>
          managedIdentity: <infrastructure_id>-identity
          networkResourceGroup: <infrastructure_id>-rg
          osDisk:
            diskSettings: {}
            diskSizeGB: 128
            managedDisk:
              storageAccountType: Premium_LRS
            osType: Linux
          publicIP: false
          publicLoadBalancer: <infrastructure_id>
          resourceGroup: <infrastructure_id>-rg
          subnet: <infrastructure_id>-worker-subnet
          userDataSecret:
            name: worker-user-data
          vmSize: Standard_D4ps_v5 2
          vnet: <infrastructure_id>-vnet
          zone: "<zone>"
1
Set the resourceID parameter to the arm64 boot image.
2
Set the vmSize parameter to the instance type used in your installation. Some example instance types are Standard_D4ps_v5 or D8ps.

Verification

  1. Verify that the new ARM64 machines are running by entering the following command: 

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                                DESIRED  CURRENT  READY  AVAILABLE  AGE
<infrastructure_id>-arm64-machine-set-0                   2        2      2          2  10m

  2. You can check that the nodes are ready and scheduable with the following command: 

    $ oc get nodes

Additional resources

4.3. Upgrading a cluster with multi-architecture compute machines

To upgrade your cluster with multi-architecture compute machines, use the candidate-4.12 update channel. For more information, see "Understanding upgrade channels".

Note

Only OpenShift Container Platform clusters that are already using a multi-architecture payload can update with the candidate-4.12 channel.

If you want to upgrade an existing cluster to support multi-architecture compute machines, you can perform an explicit upgrade command, as shown in the following procedure. This updates your current single-architecture cluster to a cluster that uses the multi-architecture payload.

Prerequisites

  • You installed the OpenShift CLI (oc).

Procedure

  • To manually upgrade your cluster, use the following command: 

    $ oc adm upgrade --allow-explicit-upgrade --to-image <image-pullspec> 1
    1
    You can access the image-pullspec object from the mixed-arch mirrors page in the release.txt file.

Additional resources

4.4. Importing manifest lists in image streams on your multi-architecture compute machines

On an OpenShift Container Platform 4.12 cluster with multi-architecture compute machines, the image streams in the cluster do not import manifest lists automatically. You must manually change the default importMode option to the PreserveOriginal option in order to import the manifest list.

Important

The referencePolicy.type field of your ImageStream object must be set to the Source type for this procedure to run successfully. 

referencePolicy:
    type: Source

Prerequisites

  • You installed the OpenShift Container Platform CLI (oc).

Procedure

  • The following example command shows how to patch the ImageStream cli-artifacts so that the cli-artifacts:latest image stream tag is imported as a manifest list. 

    oc patch is/cli-artifacts -n openshift -p '{"spec":{"tags":[{"name":"latest","importPolicy":{"importMode":"PreserveOriginal"}}]}}'

Verification

  • You can check that the manifest lists imported properly by inspecting the image stream tag. The following command will list the individual architecture manifests for a particular tag. 

    oc get istag cli-artifacts:latest -n openshift -oyaml

    If the dockerImageManifests object is present, then the manifest list import was successful.

    Example output of the dockerImageManifests object

    dockerImageManifests:
  - architecture: amd64
    digest: sha256:16d4c96c52923a9968fbfa69425ec703aff711f1db822e4e9788bf5d2bee5d77
    manifestSize: 1252
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  - architecture: arm64
    digest: sha256:6ec8ad0d897bcdf727531f7d0b716931728999492709d19d8b09f0d90d57f626
    manifestSize: 1252
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  - architecture: ppc64le
    digest: sha256:65949e3a80349cdc42acd8c5b34cde6ebc3241eae8daaeea458498fedb359a6a
    manifestSize: 1252
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux
  - architecture: s390x
    digest: sha256:75f4fa21224b5d5d511bea8f92dfa8e1c00231e5c81ab95e83c3013d245d1719
    manifestSize: 1252
    mediaType: application/vnd.docker.distribution.manifest.v2+json
    os: linux

Chapter 5. Postinstallation machine configuration tasks

There are times when you need to make changes to the operating systems running on OpenShift Container Platform nodes. This can include changing settings for network time service, adding kernel arguments, or configuring journaling in a specific way.

Aside from a few specialized features, most changes to operating systems on OpenShift Container Platform nodes can be done by creating what are referred to as MachineConfig objects that are managed by the Machine Config Operator.

Tasks in this section describe how to use features of the Machine Config Operator to configure operating system features on OpenShift Container Platform nodes.

5.1. About the Machine Config Operator

OpenShift Container Platform 4.12 integrates both operating system and cluster management. Because the cluster manages its own updates, including updates to Red Hat Enterprise Linux CoreOS (RHCOS) on cluster nodes, OpenShift Container Platform provides an opinionated lifecycle management experience that simplifies the orchestration of node upgrades.

OpenShift Container Platform employs three daemon sets and controllers to simplify node management. These daemon sets orchestrate operating system updates and configuration changes to the hosts by using standard Kubernetes-style constructs. They include:

  • The machine-config-controller, which coordinates machine upgrades from the control plane. It monitors all of the cluster nodes and orchestrates their configuration updates.
  • The machine-config-daemon daemon set, which runs on each node in the cluster and updates a machine to configuration as defined by machine config and as instructed by the MachineConfigController. When the node detects a change, it drains off its pods, applies the update, and reboots. These changes come in the form of Ignition configuration files that apply the specified machine configuration and control kubelet configuration. The update itself is delivered in a container. This process is key to the success of managing OpenShift Container Platform and RHCOS updates together.
  • The machine-config-server daemon set, which provides the Ignition config files to control plane nodes as they join the cluster.

The machine configuration is a subset of the Ignition configuration. The machine-config-daemon reads the machine configuration to see if it needs to do an OSTree update or if it must apply a series of systemd kubelet file changes, configuration changes, or other changes to the operating system or OpenShift Container Platform configuration.

When you perform node management operations, you create or modify a KubeletConfig custom resource (CR).

Important

When changes are made to a machine configuration, the Machine Config Operator (MCO) automatically reboots all corresponding nodes in order for the changes to take effect.

To prevent the nodes from automatically rebooting after machine configuration changes, before making the changes, you must pause the autoreboot process by setting the spec.paused field to true in the corresponding machine config pool. When paused, machine configuration changes are not applied until you set the spec.paused field to false and the nodes have rebooted into the new configuration.

Make sure the pools are unpaused when the CA certificate rotation happens. If the MCPs are paused, the MCO cannot push the newly rotated certificates to those nodes. This causes the cluster to become degraded and causes failure in multiple oc commands, including oc debug, oc logs, oc exec, and oc attach. You receive alerts in the Alerting UI of the OpenShift Container Platform web console if an MCP is paused when the certificates are rotated.

The following modifications do not trigger a node reboot:

  • When the MCO detects any of the following changes, it applies the update without draining or rebooting the node:

    • Changes to the SSH key in the spec.config.passwd.users.sshAuthorizedKeys parameter of a machine config.
    • Changes to the global pull secret or pull secret in the openshift-config namespace.
    • Automatic rotation of the /etc/kubernetes/kubelet-ca.crt certificate authority (CA) by the Kubernetes API Server Operator.

  • When the MCO detects changes to the /etc/containers/registries.conf file, such as adding or editing an ImageContentSourcePolicy (ICSP) object, it drains the corresponding nodes, applies the changes, and uncordons the nodes.The node drain does not happen for the following changes:

    • The addition of a registry with the pull-from-mirror = "digest-only" parameter set for each mirror.
    • The addition of a mirror with the pull-from-mirror = "digest-only" parameter set in a registry.
    • The addition of items to the unqualified-search-registries list.

There might be situations where the configuration on a node does not fully match what the currently-applied machine config specifies. This state is called configuration drift. The Machine Config Daemon (MCD) regularly checks the nodes for configuration drift. If the MCD detects configuration drift, the MCO marks the node degraded until an administrator corrects the node configuration. A degraded node is online and operational, but, it cannot be updated.

5.1.1. Machine Config overview

The Machine Config Operator (MCO) manages updates to systemd, CRI-O and Kubelet, the kernel, Network Manager and other system features. It also offers a MachineConfig CRD that can write configuration files onto the host (see machine-config-operator). Understanding what the MCO does and how it interacts with other components is critical to making advanced, system-level changes to an OpenShift Container Platform cluster. Here are some things you should know about the MCO, machine configs, and how they are used:

  • Machine configs are processed alphabetically, in lexicographically increasing order, of their name. The render controller uses the first machine config in the list as the base and appends the rest to the base machine config.
  • A machine config can make a specific change to a file or service on the operating system of each system representing a pool of OpenShift Container Platform nodes.

  • MCO applies changes to operating systems in pools of machines. All OpenShift Container Platform clusters start with worker and control plane node pools. By adding more role labels, you can configure custom pools of nodes. For example, you can set up a custom pool of worker nodes that includes particular hardware features needed by an application. However, examples in this section focus on changes to the default pool types.

    Important

    A node can have multiple labels applied that indicate its type, such as master or worker, however it can be a member of only a single machine config pool.

  • After a machine config change, the MCO updates the affected nodes alphabetically by zone, based on the topology.kubernetes.io/zone label. If a zone has more than one node, the oldest nodes are updated first. For nodes that do not use zones, such as in bare metal deployments, the nodes are upgraded by age, with the oldest nodes updated first. The MCO updates the number of nodes as specified by the maxUnavailable field on the machine configuration pool at a time.
  • Some machine configuration must be in place before OpenShift Container Platform is installed to disk. In most cases, this can be accomplished by creating a machine config that is injected directly into the OpenShift Container Platform installer process, instead of running as a postinstallation machine config. In other cases, you might need to do bare metal installation where you pass kernel arguments at OpenShift Container Platform installer startup, to do such things as setting per-node individual IP addresses or advanced disk partitioning.
  • MCO manages items that are set in machine configs. Manual changes you do to your systems will not be overwritten by MCO, unless MCO is explicitly told to manage a conflicting file. In other words, MCO only makes specific updates you request, it does not claim control over the whole node.
  • Manual changes to nodes are strongly discouraged. If you need to decommission a node and start a new one, those direct changes would be lost.
  • MCO is only supported for writing to files in /etc and /var directories, although there are symbolic links to some directories that can be writeable by being symbolically linked to one of those areas. The /opt and /usr/local directories are examples.
  • Ignition is the configuration format used in MachineConfigs. See the Ignition Configuration Specification v3.2.0 for details.
  • Although Ignition config settings can be delivered directly at OpenShift Container Platform installation time, and are formatted in the same way that MCO delivers Ignition configs, MCO has no way of seeing what those original Ignition configs are. Therefore, you should wrap Ignition config settings into a machine config before deploying them.
  • When a file managed by MCO changes outside of MCO, the Machine Config Daemon (MCD) sets the node as degraded. It will not overwrite the offending file, however, and should continue to operate in a degraded state.
  • A key reason for using a machine config is that it will be applied when you spin up new nodes for a pool in your OpenShift Container Platform cluster. The machine-api-operator provisions a new machine and MCO configures it.

MCO uses Ignition as the configuration format. OpenShift Container Platform 4.6 moved from Ignition config specification version 2 to version 3.

5.1.1.1. What can you change with machine configs?

The kinds of components that MCO can change include:

  • config: Create Ignition config objects (see the Ignition configuration specification) to do things like modify files, systemd services, and other features on OpenShift Container Platform machines, including:

    • Configuration files: Create or overwrite files in the /var or /etc directory.
    • systemd units: Create and set the status of a systemd service or add to an existing systemd service by dropping in additional settings.

    • users and groups: Change SSH keys in the passwd section postinstallation.

      Important
      • Changing SSH keys by using a machine config is supported only for the core user.
      • Adding new users by using a machine config is not supported.
  • kernelArguments: Add arguments to the kernel command line when OpenShift Container Platform nodes boot.
  • kernelType: Optionally identify a non-standard kernel to use instead of the standard kernel. Use realtime to use the RT kernel (for RAN). This is only supported on select platforms.
  • fips: Enable FIPS mode. FIPS should be set at installation-time setting and not a postinstallation procedure.
Important

To enable FIPS mode for your cluster, you must run the installation program from a Red Hat Enterprise Linux (RHEL) computer configured to operate in FIPS mode. For more information about configuring FIPS mode on RHEL, see Installing the system in FIPS mode. The use of FIPS validated or Modules In Process cryptographic libraries is only supported on OpenShift Container Platform deployments on the x86_64, ppc64le, and s390x architectures.

  • extensions: Extend RHCOS features by adding selected pre-packaged software. For this feature, available extensions include usbguard and kernel modules.
  • Custom resources (for ContainerRuntime and Kubelet): Outside of machine configs, MCO manages two special custom resources for modifying CRI-O container runtime settings (ContainerRuntime CR) and the Kubelet service (Kubelet CR).

The MCO is not the only Operator that can change operating system components on OpenShift Container Platform nodes. Other Operators can modify operating system-level features as well. One example is the Node Tuning Operator, which allows you to do node-level tuning through Tuned daemon profiles.

Tasks for the MCO configuration that can be done postinstallation are included in the following procedures. See descriptions of RHCOS bare metal installation for system configuration tasks that must be done during or before OpenShift Container Platform installation.

There might be situations where the configuration on a node does not fully match what the currently-applied machine config specifies. This state is called configuration drift. The Machine Config Daemon (MCD) regularly checks the nodes for configuration drift. If the MCD detects configuration drift, the MCO marks the node degraded until an administrator corrects the node configuration. A degraded node is online and operational, but, it cannot be updated. For more information on configuration drift, see Understanding configuration drift detection.

5.1.1.2. Project

See the openshift-machine-config-operator GitHub site for details.

5.1.2. Understanding the Machine Config Operator node drain behavior

When you use a machine config to change a system feature, such as adding new config files, modifying systemd units or kernel arguments, or updating SSH keys, the Machine Config Operator (MCO) applies those changes and ensures that each node is in the desired configuration state.

After you make the changes, the MCO generates a new rendered machine config. In the majority of cases, when applying the new rendered machine config, the Operator performs the following steps on each affected node until all of the affected nodes have the updated configuration:

  1. Cordon. The MCO marks the node as not schedulable for additional workloads.
  2. Drain. The MCO terminates all running workloads on the node, causing the workloads to be rescheduled onto other nodes.
  3. Apply. The MCO writes the new configuration to the nodes as needed.
  4. Reboot. The MCO restarts the node.
  5. Uncordon. The MCO marks the node as schedulable for workloads.

Throughout this process, the MCO maintains the required number of pods based on the MaxUnavailable value set in the machine config pool.

If the MCO drains pods on the master node, note the following conditions:

  • In single-node OpenShift clusters, the MCO skips the drain operation.
  • The MCO does not drain static pods in order to prevent interference with services, such as etcd.
Note

In certain cases the nodes are not drained. For more information, see "About the Machine Config Operator."

You can mitigate the disruption caused by drain and reboot cycles by disabling control plane reboots. For more information, see "Disabling the Machine Config Operator from automatically rebooting."

Additional resources

5.1.3. Understanding configuration drift detection

There might be situations when the on-disk state of a node differs from what is configured in the machine config. This is known as configuration drift. For example, a cluster admin might manually modify a file, a systemd unit file, or a file permission that was configured through a machine config. This causes configuration drift. Configuration drift can cause problems between nodes in a Machine Config Pool or when the machine configs are updated.

The Machine Config Operator (MCO) uses the Machine Config Daemon (MCD) to check nodes for configuration drift on a regular basis. If detected, the MCO sets the node and the machine config pool (MCP) to Degraded and reports the error. A degraded node is online and operational, but, it cannot be updated.

The MCD performs configuration drift detection upon each of the following conditions:

  • When a node boots.
  • After any of the files (Ignition files and systemd drop-in units) specified in the machine config are modified outside of the machine config.

  • Before a new machine config is applied.

    Note

    If you apply a new machine config to the nodes, the MCD temporarily shuts down configuration drift detection. This shutdown is needed because the new machine config necessarily differs from the machine config on the nodes. After the new machine config is applied, the MCD restarts detecting configuration drift using the new machine config.

When performing configuration drift detection, the MCD validates that the file contents and permissions fully match what the currently-applied machine config specifies. Typically, the MCD detects configuration drift in less than a second after the detection is triggered.

If the MCD detects configuration drift, the MCD performs the following tasks:

  • Emits an error to the console logs
  • Emits a Kubernetes event
  • Stops further detection on the node
  • Sets the node and MCP to degraded

You can check if you have a degraded node by listing the MCPs: 

$ oc get mcp worker

If you have a degraded MCP, the DEGRADEDMACHINECOUNT field is non-zero, similar to the following output:

Example output

NAME     CONFIG                                             UPDATED   UPDATING   DEGRADED   MACHINECOUNT   READYMACHINECOUNT   UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
worker   rendered-worker-404caf3180818d8ac1f50c32f14b57c3   False     True       True       2              1                   1                     1                      5h51m

You can determine if the problem is caused by configuration drift by examining the machine config pool: 

$ oc describe mcp worker

Example output

 ...
    Last Transition Time:  2021-12-20T18:54:00Z
    Message:               Node ci-ln-j4h8nkb-72292-pxqxz-worker-a-fjks4 is reporting: "content mismatch for file \"/etc/mco-test-file\"" 1
    Reason:                1 nodes are reporting degraded status on sync
    Status:                True
    Type:                  NodeDegraded 2
 ...

1
This message shows that a node’s /etc/mco-test-file file, which was added by the machine config, has changed outside of the machine config.
2
The state of the node is NodeDegraded.

Or, if you know which node is degraded, examine that node: 

$ oc describe node/ci-ln-j4h8nkb-72292-pxqxz-worker-a-fjks4

Example output

 ...

Annotations:        cloud.network.openshift.io/egress-ipconfig: [{"interface":"nic0","ifaddr":{"ipv4":"10.0.128.0/17"},"capacity":{"ip":10}}]
                    csi.volume.kubernetes.io/nodeid:
                      {"pd.csi.storage.gke.io":"projects/openshift-gce-devel-ci/zones/us-central1-a/instances/ci-ln-j4h8nkb-72292-pxqxz-worker-a-fjks4"}
                    machine.openshift.io/machine: openshift-machine-api/ci-ln-j4h8nkb-72292-pxqxz-worker-a-fjks4
                    machineconfiguration.openshift.io/controlPlaneTopology: HighlyAvailable
                    machineconfiguration.openshift.io/currentConfig: rendered-worker-67bd55d0b02b0f659aef33680693a9f9
                    machineconfiguration.openshift.io/desiredConfig: rendered-worker-67bd55d0b02b0f659aef33680693a9f9
                    machineconfiguration.openshift.io/reason: content mismatch for file "/etc/mco-test-file" 1
                    machineconfiguration.openshift.io/state: Degraded 2
 ...

1
The error message indicating that configuration drift was detected between the node and the listed machine config. Here the error message indicates that the contents of the /etc/mco-test-file, which was added by the machine config, has changed outside of the machine config.
2
The state of the node is Degraded.

You can correct configuration drift and return the node to the Ready state by performing one of the following remediations:

  • Ensure that the contents and file permissions of the files on the node match what is configured in the machine config. You can manually rewrite the file contents or change the file permissions.

  • Generate a force file on the degraded node. The force file causes the MCD to bypass the usual configuration drift detection and reapplies the current machine config.

    Note

    Generating a force file on a node causes that node to reboot.

Additional resources

5.1.4. Checking machine config pool status

To see the status of the Machine Config Operator (MCO), its sub-components, and the resources it manages, use the following oc commands:

Procedure

  1. To see the number of MCO-managed nodes available on your cluster for each machine config pool (MCP), run the following command: 

    $ oc get machineconfigpool

    Example output

    NAME      CONFIG                    UPDATED  UPDATING   DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT DEGRADEDMACHINECOUNT  AGE
master    rendered-master-06c9c4…   True     False      False     3             3                  3                   0                     4h42m
worker    rendered-worker-f4b64…    False    True       False     3             2                  2                   0                     4h42m

    where:

    UPDATED
    The True status indicates that the MCO has applied the current machine config to the nodes in that MCP. The current machine config is specified in the STATUS field in the oc get mcp output. The False status indicates a node in the MCP is updating.
    UPDATING
    The True status indicates that the MCO is applying the desired machine config, as specified in the MachineConfigPool custom resource, to at least one of the nodes in that MCP. The desired machine config is the new, edited machine config. Nodes that are updating might not be available for scheduling. The False status indicates that all nodes in the MCP are updated.
    DEGRADED
    A True status indicates the MCO is blocked from applying the current or desired machine config to at least one of the nodes in that MCP, or the configuration is failing. Nodes that are degraded might not be available for scheduling. A False status indicates that all nodes in the MCP are ready.
    MACHINECOUNT
    Indicates the total number of machines in that MCP.
    READYMACHINECOUNT
    Indicates the total number of machines in that MCP that are ready for scheduling.
    UPDATEDMACHINECOUNT
    Indicates the total number of machines in that MCP that have the current machine config.
    DEGRADEDMACHINECOUNT
    Indicates the total number of machines in that MCP that are marked as degraded or unreconcilable.

    In the previous output, there are three control plane (master) nodes and three worker nodes. The control plane MCP and the associated nodes are updated to the current machine config. The nodes in the worker MCP are being updated to the desired machine config. Two of the nodes in the worker MCP are updated and one is still updating, as indicated by the UPDATEDMACHINECOUNT being 2. There are no issues, as indicated by the DEGRADEDMACHINECOUNT being 0 and DEGRADED being False.

    While the nodes in the MCP are updating, the machine config listed under CONFIG is the current machine config, which the MCP is being updated from. When the update is complete, the listed machine config is the desired machine config, which the MCP was updated to.

    Note

    If a node is being cordoned, that node is not included in the READYMACHINECOUNT, but is included in the MACHINECOUNT. Also, the MCP status is set to UPDATING. Because the node has the current machine config, it is counted in the UPDATEDMACHINECOUNT total:

    Example output

    NAME      CONFIG                    UPDATED  UPDATING   DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT DEGRADEDMACHINECOUNT  AGE
master    rendered-master-06c9c4…   True     False      False     3             3                  3                   0                     4h42m
worker    rendered-worker-c1b41a…   False    True       False     3             2                  3                   0                     4h42m

  2. To check the status of the nodes in an MCP by examining the MachineConfigPool custom resource, run the following command: : 

    $ oc describe mcp worker

    Example output

    ...
  Degraded Machine Count:     0
  Machine Count:              3
  Observed Generation:        2
  Ready Machine Count:        3
  Unavailable Machine Count:  0
  Updated Machine Count:      3
Events:                       <none>

    Note

    If a node is being cordoned, the node is not included in the Ready Machine Count. It is included in the Unavailable Machine Count:

    Example output

    ...
  Degraded Machine Count:     0
  Machine Count:              3
  Observed Generation:        2
  Ready Machine Count:        2
  Unavailable Machine Count:  1
  Updated Machine Count:      3

  3. To see each existing MachineConfig object, run the following command: 

    $ oc get machineconfigs

    Example output

    NAME                             GENERATEDBYCONTROLLER          IGNITIONVERSION  AGE
00-master                        2c9371fbb673b97a6fe8b1c52...   3.2.0            5h18m
00-worker                        2c9371fbb673b97a6fe8b1c52...   3.2.0            5h18m
01-master-container-runtime      2c9371fbb673b97a6fe8b1c52...   3.2.0            5h18m
01-master-kubelet                2c9371fbb673b97a6fe8b1c52…     3.2.0            5h18m
...
rendered-master-dde...           2c9371fbb673b97a6fe8b1c52...   3.2.0            5h18m
rendered-worker-fde...           2c9371fbb673b97a6fe8b1c52...   3.2.0            5h18m

    Note that the MachineConfig objects listed as rendered are not meant to be changed or deleted.

  4. To view the contents of a particular machine config (in this case, 01-master-kubelet), run the following command: 

    $ oc describe machineconfigs 01-master-kubelet

    The output from the command shows that this MachineConfig object contains both configuration files (cloud.conf and kubelet.conf) and a systemd service (Kubernetes Kubelet):

    Example output

    Name:         01-master-kubelet
...
Spec:
  Config:
    Ignition:
      Version:  3.2.0
    Storage:
      Files:
        Contents:
          Source:   data:,
        Mode:       420
        Overwrite:  true
        Path:       /etc/kubernetes/cloud.conf
        Contents:
          Source:   data:,kind%3A%20KubeletConfiguration%0AapiVersion%3A%20kubelet.config.k8s.io%2Fv1beta1%0Aauthentication%3A%0A%20%20x509%3A%0A%20%20%20%20clientCAFile%3A%20%2Fetc%2Fkubernetes%2Fkubelet-ca.crt%0A%20%20anonymous...
        Mode:       420
        Overwrite:  true
        Path:       /etc/kubernetes/kubelet.conf
    Systemd:
      Units:
        Contents:  [Unit]
Description=Kubernetes Kubelet
Wants=rpc-statd.service network-online.target crio.service
After=network-online.target crio.service

ExecStart=/usr/bin/hyperkube \
    kubelet \
      --config=/etc/kubernetes/kubelet.conf \ ...

If something goes wrong with a machine config that you apply, you can always back out that change. For example, if you had run oc create -f ./myconfig.yaml to apply a machine config, you could remove that machine config by running the following command: 

$ oc delete -f ./myconfig.yaml

If that was the only problem, the nodes in the affected pool should return to a non-degraded state. This actually causes the rendered configuration to roll back to its previously rendered state.

If you add your own machine configs to your cluster, you can use the commands shown in the previous example to check their status and the related status of the pool to which they are applied.

5.2. Using MachineConfig objects to configure nodes

You can use the tasks in this section to create MachineConfig objects that modify files, systemd unit files, and other operating system features running on OpenShift Container Platform nodes. For more ideas on working with machine configs, see content related to updating SSH authorized keys, verifying image signatures, enabling SCTP, and configuring iSCSI initiatornames for OpenShift Container Platform.

OpenShift Container Platform supports Ignition specification version 3.2. All new machine configs you create going forward should be based on Ignition specification version 3.2. If you are upgrading your OpenShift Container Platform cluster, any existing Ignition specification version 2.x machine configs will be translated automatically to specification version 3.2.

There might be situations where the configuration on a node does not fully match what the currently-applied machine config specifies. This state is called configuration drift. The Machine Config Daemon (MCD) regularly checks the nodes for configuration drift. If the MCD detects configuration drift, the MCO marks the node degraded until an administrator corrects the node configuration. A degraded node is online and operational, but, it cannot be updated. For more information on configuration drift, see Understanding configuration drift detection.

Tip

Use the following "Configuring chrony time service" procedure as a model for how to go about adding other configuration files to OpenShift Container Platform nodes.

5.2.1. Configuring chrony time service

You can set the time server and related settings used by the chrony time service (chronyd) by modifying the contents of the chrony.conf file and passing those contents to your nodes as a machine config.

Procedure

  1. Create a Butane config including the contents of the chrony.conf file. For example, to configure chrony on worker nodes, create a 99-worker-chrony.bu file.

    Note

    See "Creating machine configs with Butane" for information about Butane. 

    variant: openshift
version: 4.12.0
metadata:
  name: 99-worker-chrony 1
  labels:
    machineconfiguration.openshift.io/role: worker 2
storage:
  files:
  - path: /etc/chrony.conf
    mode: 0644 3
    overwrite: true
    contents:
      inline: |
        pool 0.rhel.pool.ntp.org iburst 4
        driftfile /var/lib/chrony/drift
        makestep 1.0 3
        rtcsync
        logdir /var/log/chrony
    1 2
    On control plane nodes, substitute master for worker in both of these locations.
    3
    Specify an octal value mode for the mode field in the machine config file. After creating the file and applying the changes, the mode is converted to a decimal value. You can check the YAML file with the command oc get mc <mc-name> -o yaml.
    4
    Specify any valid, reachable time source, such as the one provided by your DHCP server. Alternately, you can specify any of the following NTP servers: 1.rhel.pool.ntp.org, 2.rhel.pool.ntp.org, or 3.rhel.pool.ntp.org.

  2. Use Butane to generate a MachineConfig object file, 99-worker-chrony.yaml, containing the configuration to be delivered to the nodes: 

    $ butane 99-worker-chrony.bu -o 99-worker-chrony.yaml

  3. Apply the configurations in one of two ways:

    • If the cluster is not running yet, after you generate manifest files, add the MachineConfig object file to the <installation_directory>/openshift directory, and then continue to create the cluster.

    • If the cluster is already running, apply the file: 

      $ oc apply -f ./99-worker-chrony.yaml

Additional resources

5.2.2. Disabling the chrony time service

You can disable the chrony time service (chronyd) for nodes with a specific role by using a MachineConfig custom resource (CR).

Prerequisites

  • Install the OpenShift CLI (oc).
  • Log in as a user with cluster-admin privileges.

Procedure

  1. Create the MachineConfig CR that disables chronyd for the specified node role.

    1. Save the following YAML in the disable-chronyd.yaml file: 

      apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: <node_role> 1
  name: disable-chronyd
spec:
  config:
    ignition:
      version: 3.2.0
    systemd:
      units:
        - contents: |
            [Unit]
            Description=NTP client/server
            Documentation=man:chronyd(8) man:chrony.conf(5)
            After=ntpdate.service sntp.service ntpd.service
            Conflicts=ntpd.service systemd-timesyncd.service
            ConditionCapability=CAP_SYS_TIME
            [Service]
            Type=forking
            PIDFile=/run/chrony/chronyd.pid
            EnvironmentFile=-/etc/sysconfig/chronyd
            ExecStart=/usr/sbin/chronyd $OPTIONS
            ExecStartPost=/usr/libexec/chrony-helper update-daemon
            PrivateTmp=yes
            ProtectHome=yes
            ProtectSystem=full
            [Install]
            WantedBy=multi-user.target
          enabled: false
          name: "chronyd.service"
      1
      Node role where you want to disable chronyd, for example, master.

    2. Create the MachineConfig CR by running the following command: 

      $ oc create -f disable-chronyd.yaml

5.2.3. Adding kernel arguments to nodes

In some special cases, you might want to add kernel arguments to a set of nodes in your cluster. This should only be done with caution and clear understanding of the implications of the arguments you set.

Warning

Improper use of kernel arguments can result in your systems becoming unbootable.

Examples of kernel arguments you could set include:

  • nosmt: Disables symmetric multithreading (SMT) in the kernel. Multithreading allows multiple logical threads for each CPU. You could consider nosmt in multi-tenant environments to reduce risks from potential cross-thread attacks. By disabling SMT, you essentially choose security over performance.

  • systemd.unified_cgroup_hierarchy: Enables Linux control group version 2 (cgroup v2). cgroup v2 is the next version of the kernel control group and offers multiple improvements.

    Important

    OpenShift Container Platform cgroups version 2 support is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

    For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

  • enforcing=0: Configures Security Enhanced Linux (SELinux) to run in permissive mode. In permissive mode, the system acts as if SELinux is enforcing the loaded security policy, including labeling objects and emitting access denial entries in the logs, but it does not actually deny any operations. While not supported for production systems, permissive mode can be helpful for debugging.

    Warning

    Disabling SELinux on RHCOS in production is not supported. Once SELinux has been disabled on a node, it must be re-provisioned before re-inclusion in a production cluster.

See Kernel.org kernel parameters for a list and descriptions of kernel arguments.

In the following procedure, you create a MachineConfig object that identifies:

  • A set of machines to which you want to add the kernel argument. In this case, machines with a worker role.
  • Kernel arguments that are appended to the end of the existing kernel arguments.
  • A label that indicates where in the list of machine configs the change is applied.

Prerequisites

  • Have administrative privilege to a working OpenShift Container Platform cluster.

Procedure

  1. List existing MachineConfig objects for your OpenShift Container Platform cluster to determine how to label your machine config: 

    $ oc get MachineConfig

    Example output

    NAME                                               GENERATEDBYCONTROLLER                      IGNITIONVERSION   AGE
00-master                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
00-worker                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-master-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-master-ssh                                                                                 3.2.0             40m
99-worker-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-worker-ssh                                                                                 3.2.0             40m
rendered-master-23e785de7587df95a4b517e0647e5ab7   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
rendered-worker-5d596d9293ca3ea80c896a1191735bb1   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m

  2. Create a MachineConfig object file that identifies the kernel argument (for example, 05-worker-kernelarg-selinuxpermissive.yaml) 

    apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker1
  name: 05-worker-kernelarg-selinuxpermissive2
spec:
  kernelArguments:
    - enforcing=03
    1
    Applies the new kernel argument only to worker nodes.
    2
    Named to identify where it fits among the machine configs (05) and what it does (adds a kernel argument to configure SELinux permissive mode).
    3
    Identifies the exact kernel argument as enforcing=0.

  3. Create the new machine config: 

    $ oc create -f 05-worker-kernelarg-selinuxpermissive.yaml

  4. Check the machine configs to see that the new one was added: 

    $ oc get MachineConfig

    Example output

    NAME                                               GENERATEDBYCONTROLLER                      IGNITIONVERSION   AGE
00-master                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
00-worker                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
05-worker-kernelarg-selinuxpermissive                                                         3.2.0             105s
99-master-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-master-ssh                                                                                 3.2.0             40m
99-worker-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-worker-ssh                                                                                 3.2.0             40m
rendered-master-23e785de7587df95a4b517e0647e5ab7   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
rendered-worker-5d596d9293ca3ea80c896a1191735bb1   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m

  5. Check the nodes: 

    $ oc get nodes

    Example output

    NAME                           STATUS                     ROLES    AGE   VERSION
ip-10-0-136-161.ec2.internal   Ready                      worker   28m   v1.25.0
ip-10-0-136-243.ec2.internal   Ready                      master   34m   v1.25.0
ip-10-0-141-105.ec2.internal   Ready,SchedulingDisabled   worker   28m   v1.25.0
ip-10-0-142-249.ec2.internal   Ready                      master   34m   v1.25.0
ip-10-0-153-11.ec2.internal    Ready                      worker   28m   v1.25.0
ip-10-0-153-150.ec2.internal   Ready                      master   34m   v1.25.0

    You can see that scheduling on each worker node is disabled as the change is being applied.

  6. Check that the kernel argument worked by going to one of the worker nodes and listing the kernel command line arguments (in /proc/cmdline on the host): 

    $ oc debug node/ip-10-0-141-105.ec2.internal

    Example output

    Starting pod/ip-10-0-141-105ec2internal-debug ...
To use host binaries, run `chroot /host`

sh-4.2# cat /host/proc/cmdline
BOOT_IMAGE=/ostree/rhcos-... console=tty0 console=ttyS0,115200n8
rootflags=defaults,prjquota rw root=UUID=fd0... ostree=/ostree/boot.0/rhcos/16...
coreos.oem.id=qemu coreos.oem.id=ec2 ignition.platform.id=ec2 enforcing=0

sh-4.2# exit

    You should see the enforcing=0 argument added to the other kernel arguments.

5.2.4. Enabling multipathing with kernel arguments on RHCOS

Red Hat Enterprise Linux CoreOS (RHCOS) supports multipathing on the primary disk, allowing stronger resilience to hardware failure to achieve higher host availability. Postinstallation support is available by activating multipathing via the machine config.

Important

Enabling multipathing during installation is supported and recommended for nodes provisioned in OpenShift Container Platform 4.8 or higher. In setups where any I/O to non-optimized paths results in I/O system errors, you must enable multipathing at installation time. For more information about enabling multipathing during installation time, see "Enabling multipathing with kernel arguments on RHCOS" in the Installing on bare metal documentation.

Important

On IBM Z and IBM® LinuxONE, you can enable multipathing only if you configured your cluster for it during installation. For more information, see "Installing RHCOS and starting the OpenShift Container Platform bootstrap process" in Installing a cluster with z/VM on IBM Z and IBM® LinuxONE.

Important

When a OpenShift Container Platform 4.12 cluster is installed or configured as a post-installation activity on a single VIOS host with "vSCSI" storage on IBM Power® with multipath configured, the CoreOS nodes with multipath enabled fail to boot. This behavior is expected, as only one path is available to the Node.

Prerequisites

  • You have a running OpenShift Container Platform cluster that uses version 4.7 or later.
  • You are logged in to the cluster as a user with administrative privileges.
  • You have confirmed that the disk is enabled for multipathing. Multipathing is only supported on hosts that are connected to a SAN via an HBA adapter.

Procedure

  1. To enable multipathing postinstallation on control plane nodes:

    • Create a machine config file, such as 99-master-kargs-mpath.yaml, that instructs the cluster to add the master label and that identifies the multipath kernel argument, for example: 

      apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: "master"
  name: 99-master-kargs-mpath
spec:
  kernelArguments:
    - 'rd.multipath=default'
    - 'root=/dev/disk/by-label/dm-mpath-root'

  2. To enable multipathing postinstallation on worker nodes:

    • Create a machine config file, such as 99-worker-kargs-mpath.yaml, that instructs the cluster to add the worker label and that identifies the multipath kernel argument, for example: 

      apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: "worker"
  name: 99-worker-kargs-mpath
spec:
  kernelArguments:
    - 'rd.multipath=default'
    - 'root=/dev/disk/by-label/dm-mpath-root'

  3. Create the new machine config by using either the master or worker YAML file you previously created: 

    $ oc create -f ./99-worker-kargs-mpath.yaml

  4. Check the machine configs to see that the new one was added: 

    $ oc get MachineConfig

    Example output

    NAME                                               GENERATEDBYCONTROLLER                      IGNITIONVERSION   AGE
00-master                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
00-worker                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-master-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-master-ssh                                                                                 3.2.0             40m
99-worker-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-worker-kargs-mpath                              52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             105s
99-worker-ssh                                                                                 3.2.0             40m
rendered-master-23e785de7587df95a4b517e0647e5ab7   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
rendered-worker-5d596d9293ca3ea80c896a1191735bb1   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m

  5. Check the nodes: 

    $ oc get nodes

    Example output

    NAME                           STATUS                     ROLES    AGE   VERSION
ip-10-0-136-161.ec2.internal   Ready                      worker   28m   v1.25.0
ip-10-0-136-243.ec2.internal   Ready                      master   34m   v1.25.0
ip-10-0-141-105.ec2.internal   Ready,SchedulingDisabled   worker   28m   v1.25.0
ip-10-0-142-249.ec2.internal   Ready                      master   34m   v1.25.0
ip-10-0-153-11.ec2.internal    Ready                      worker   28m   v1.25.0
ip-10-0-153-150.ec2.internal   Ready                      master   34m   v1.25.0

    You can see that scheduling on each worker node is disabled as the change is being applied.

  6. Check that the kernel argument worked by going to one of the worker nodes and listing the kernel command line arguments (in /proc/cmdline on the host): 

    $ oc debug node/ip-10-0-141-105.ec2.internal

    Example output

    Starting pod/ip-10-0-141-105ec2internal-debug ...
To use host binaries, run `chroot /host`

sh-4.2# cat /host/proc/cmdline
...
rd.multipath=default root=/dev/disk/by-label/dm-mpath-root
...

sh-4.2# exit

    You should see the added kernel arguments.

Additional resources

5.2.5. Adding a real-time kernel to nodes

Some OpenShift Container Platform workloads require a high degree of determinism.While Linux is not a real-time operating system, the Linux real-time kernel includes a preemptive scheduler that provides the operating system with real-time characteristics.

If your OpenShift Container Platform workloads require these real-time characteristics, you can switch your machines to the Linux real-time kernel. For OpenShift Container Platform, 4.12 you can make this switch using a MachineConfig object. Although making the change is as simple as changing a machine config kernelType setting to realtime, there are a few other considerations before making the change:

  • Currently, real-time kernel is supported only on worker nodes, and only for radio access network (RAN) use.
  • The following procedure is fully supported with bare metal installations that use systems that are certified for Red Hat Enterprise Linux for Real Time 8.
  • Real-time support in OpenShift Container Platform is limited to specific subscriptions.
  • The following procedure is also supported for use with Google Cloud Platform.

Prerequisites

  • Have a running OpenShift Container Platform cluster (version 4.4 or later).
  • Log in to the cluster as a user with administrative privileges.

Procedure

  1. Create a machine config for the real-time kernel: Create a YAML file (for example, 99-worker-realtime.yaml) that contains a MachineConfig object for the realtime kernel type. This example tells the cluster to use a real-time kernel for all worker nodes: 

    $ cat << EOF > 99-worker-realtime.yaml
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: "worker"
  name: 99-worker-realtime
spec:
  kernelType: realtime
EOF

  2. Add the machine config to the cluster. Type the following to add the machine config to the cluster: 

    $ oc create -f 99-worker-realtime.yaml

  3. Check the real-time kernel: Once each impacted node reboots, log in to the cluster and run the following commands to make sure that the real-time kernel has replaced the regular kernel for the set of nodes you configured: 

    $ oc get nodes

    Example output

    NAME                                        STATUS  ROLES    AGE   VERSION
ip-10-0-143-147.us-east-2.compute.internal  Ready   worker   103m  v1.25.0
ip-10-0-146-92.us-east-2.compute.internal   Ready   worker   101m  v1.25.0
ip-10-0-169-2.us-east-2.compute.internal    Ready   worker   102m  v1.25.0

    $ oc debug node/ip-10-0-143-147.us-east-2.compute.internal

    Example output

    Starting pod/ip-10-0-143-147us-east-2computeinternal-debug ...
To use host binaries, run `chroot /host`

sh-4.4# uname -a
Linux <worker_node> 4.18.0-147.3.1.rt24.96.el8_1.x86_64 #1 SMP PREEMPT RT
        Wed Nov 27 18:29:55 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

    The kernel name contains rt and text “PREEMPT RT” indicates that this is a real-time kernel.

  4. To go back to the regular kernel, delete the MachineConfig object: 

    $ oc delete -f 99-worker-realtime.yaml

5.2.6. Configuring journald settings

If you need to configure settings for the journald service on OpenShift Container Platform nodes, you can do that by modifying the appropriate configuration file and passing the file to the appropriate pool of nodes as a machine config.

This procedure describes how to modify journald rate limiting settings in the /etc/systemd/journald.conf file and apply them to worker nodes. See the journald.conf man page for information on how to use that file.

Prerequisites

  • Have a running OpenShift Container Platform cluster.
  • Log in to the cluster as a user with administrative privileges.

Procedure

  1. Create a Butane config file, 40-worker-custom-journald.bu, that includes an /etc/systemd/journald.conf file with the required settings.

    Note

    See "Creating machine configs with Butane" for information about Butane. 

    variant: openshift
version: 4.12.0
metadata:
  name: 40-worker-custom-journald
  labels:
    machineconfiguration.openshift.io/role: worker
storage:
  files:
  - path: /etc/systemd/journald.conf
    mode: 0644
    overwrite: true
    contents:
      inline: |
        # Disable rate limiting
        RateLimitInterval=1s
        RateLimitBurst=10000
        Storage=volatile
        Compress=no
        MaxRetentionSec=30s

  2. Use Butane to generate a MachineConfig object file, 40-worker-custom-journald.yaml, containing the configuration to be delivered to the worker nodes: 

    $ butane 40-worker-custom-journald.bu -o 40-worker-custom-journald.yaml

  3. Apply the machine config to the pool: 

    $ oc apply -f 40-worker-custom-journald.yaml

  4. Check that the new machine config is applied and that the nodes are not in a degraded state. It might take a few minutes. The worker pool will show the updates in progress, as each node successfully has the new machine config applied: 

    $ oc get machineconfigpool
NAME   CONFIG             UPDATED UPDATING DEGRADED MACHINECOUNT READYMACHINECOUNT UPDATEDMACHINECOUNT DEGRADEDMACHINECOUNT AGE
master rendered-master-35 True    False    False    3            3                 3                   0                    34m
worker rendered-worker-d8 False   True     False    3            1                 1                   0                    34m

  5. To check that the change was applied, you can log in to a worker node: 

    $ oc get node | grep worker
ip-10-0-0-1.us-east-2.compute.internal   Ready    worker   39m   v0.0.0-master+$Format:%h$
$ oc debug node/ip-10-0-0-1.us-east-2.compute.internal
Starting pod/ip-10-0-141-142us-east-2computeinternal-debug ...
...
sh-4.2# chroot /host
sh-4.4# cat /etc/systemd/journald.conf
# Disable rate limiting
RateLimitInterval=1s
RateLimitBurst=10000
Storage=volatile
Compress=no
MaxRetentionSec=30s
sh-4.4# exit

Additional resources

5.2.7. Adding extensions to RHCOS

RHCOS is a minimal container-oriented RHEL operating system, designed to provide a common set of capabilities to OpenShift Container Platform clusters across all platforms. While adding software packages to RHCOS systems is generally discouraged, the MCO provides an extensions feature you can use to add a minimal set of features to RHCOS nodes.

Currently, the following extensions are available:

  • usbguard: Adding the usbguard extension protects RHCOS systems from attacks from intrusive USB devices. See USBGuard for details.
  • kerberos: Adding the kerberos extension provides a mechanism that allows both users and machines to identify themselves to the network to receive defined, limited access to the areas and services that an administrator has configured. See Using Kerberos for details, including how to set up a Kerberos client and mount a Kerberized NFS share.

The following procedure describes how to use a machine config to add one or more extensions to your RHCOS nodes.

Prerequisites

  • Have a running OpenShift Container Platform cluster (version 4.6 or later).
  • Log in to the cluster as a user with administrative privileges.

Procedure

  1. Create a machine config for extensions: Create a YAML file (for example, 80-extensions.yaml) that contains a MachineConfig extensions object. This example tells the cluster to add the usbguard extension. 

    $ cat << EOF > 80-extensions.yaml
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 80-worker-extensions
spec:
  config:
    ignition:
      version: 3.2.0
  extensions:
    - usbguard
EOF

  2. Add the machine config to the cluster. Type the following to add the machine config to the cluster: 

    $ oc create -f 80-extensions.yaml

    This sets all worker nodes to have rpm packages for usbguard installed.

  3. Check that the extensions were applied: 

    $ oc get machineconfig 80-worker-extensions

    Example output

    NAME                 GENERATEDBYCONTROLLER IGNITIONVERSION AGE
80-worker-extensions                       3.2.0           57s

  4. Check that the new machine config is now applied and that the nodes are not in a degraded state. It may take a few minutes. The worker pool will show the updates in progress, as each machine successfully has the new machine config applied: 

    $ oc get machineconfigpool

    Example output

    NAME   CONFIG             UPDATED UPDATING DEGRADED MACHINECOUNT READYMACHINECOUNT UPDATEDMACHINECOUNT DEGRADEDMACHINECOUNT AGE
master rendered-master-35 True    False    False    3            3                 3                   0                    34m
worker rendered-worker-d8 False   True     False    3            1                 1                   0                    34m

  5. Check the extensions. To check that the extension was applied, run: 

    $ oc get node | grep worker

    Example output

    NAME                                        STATUS  ROLES    AGE   VERSION
ip-10-0-169-2.us-east-2.compute.internal    Ready   worker   102m  v1.25.0

    $ oc debug node/ip-10-0-169-2.us-east-2.compute.internal

    Example output

    ...
To use host binaries, run `chroot /host`
sh-4.4# chroot /host
sh-4.4# rpm -q usbguard
usbguard-0.7.4-4.el8.x86_64.rpm

5.2.8. Loading custom firmware blobs in the machine config manifest

Because the default location for firmware blobs in /usr/lib is read-only, you can locate a custom firmware blob by updating the search path. This enables you to load local firmware blobs in the machine config manifest when the blobs are not managed by RHCOS.

Procedure

  1. Create a Butane config file, 98-worker-firmware-blob.bu, that updates the search path so that it is root-owned and writable to local storage. The following example places the custom blob file from your local workstation onto nodes under /var/lib/firmware.

    Note

    See "Creating machine configs with Butane" for information about Butane.

    Butane config file for custom firmware blob

    variant: openshift
version: 4.12.0
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 98-worker-firmware-blob
storage:
  files:
  - path: /var/lib/firmware/<package_name> 1
    contents:
      local: <package_name> 2
    mode: 0644 3
openshift:
  kernel_arguments:
    - 'firmware_class.path=/var/lib/firmware' 4

    1
    Sets the path on the node where the firmware package is copied to.
    2
    Specifies a file with contents that are read from a local file directory on the system running Butane. The path of the local file is relative to a files-dir directory, which must be specified by using the --files-dir option with Butane in the following step.
    3
    Sets the permissions for the file on the RHCOS node. It is recommended to set 0644 permissions.
    4
    The firmware_class.path parameter customizes the kernel search path of where to look for the custom firmware blob that was copied from your local workstation onto the root file system of the node. This example uses /var/lib/firmware as the customized path.

  2. Run Butane to generate a MachineConfig object file that uses a copy of the firmware blob on your local workstation named 98-worker-firmware-blob.yaml. The firmware blob contains the configuration to be delivered to the nodes. The following example uses the --files-dir option to specify the directory on your workstation where the local file or files are located: 

    $ butane 98-worker-firmware-blob.bu -o 98-worker-firmware-blob.yaml --files-dir <directory_including_package_name>

  3. Apply the configurations to the nodes in one of two ways:

    • If the cluster is not running yet, after you generate manifest files, add the MachineConfig object file to the <installation_directory>/openshift directory, and then continue to create the cluster.

    • If the cluster is already running, apply the file: 

      $ oc apply -f 98-worker-firmware-blob.yaml

      A MachineConfig object YAML file is created for you to finish configuring your machines.

  4. Save the Butane config in case you need to update the MachineConfig object in the future.

Additional resources

5.3. Configuring MCO-related custom resources

Besides managing MachineConfig objects, the MCO manages two custom resources (CRs): KubeletConfig and ContainerRuntimeConfig. Those CRs let you change node-level settings impacting how the Kubelet and CRI-O container runtime services behave.

5.3.1. Creating a KubeletConfig CRD to edit kubelet parameters

The kubelet configuration is currently serialized as an Ignition configuration, so it can be directly edited. However, there is also a new kubelet-config-controller added to the Machine Config Controller (MCC). This lets you use a KubeletConfig custom resource (CR) to edit the kubelet parameters.

Note

As the fields in the kubeletConfig object are passed directly to the kubelet from upstream Kubernetes, the kubelet validates those values directly. Invalid values in the kubeletConfig object might cause cluster nodes to become unavailable. For valid values, see the Kubernetes documentation.

Consider the following guidance:

  • Edit an existing KubeletConfig CR to modify existing settings or add new settings, instead of creating a CR for each change. It is recommended that you create a CR only to modify a different machine config pool, or for changes that are intended to be temporary, so that you can revert the changes.
  • Create one KubeletConfig CR for each machine config pool with all the config changes you want for that pool.
  • As needed, create multiple KubeletConfig CRs with a limit of 10 per cluster. For the first KubeletConfig CR, the Machine Config Operator (MCO) creates a machine config appended with kubelet. With each subsequent CR, the controller creates another kubelet machine config with a numeric suffix. For example, if you have a kubelet machine config with a -2 suffix, the next kubelet machine config is appended with -3.
Note

If you are applying a kubelet or container runtime config to a custom machine config pool, the custom role in the machineConfigSelector must match the name of the custom machine config pool.

For example, because the following custom machine config pool is named infra, the custom role must also be infra: 

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfigPool
metadata:
  name: infra
spec:
  machineConfigSelector:
    matchExpressions:
      - {key: machineconfiguration.openshift.io/role, operator: In, values: [worker,infra]}
# ...

If you want to delete the machine configs, delete them in reverse order to avoid exceeding the limit. For example, you delete the kubelet-3 machine config before deleting the kubelet-2 machine config.

Note

If you have a machine config with a kubelet-9 suffix, and you create another KubeletConfig CR, a new machine config is not created, even if there are fewer than 10 kubelet machine configs.

Example KubeletConfig CR

$ oc get kubeletconfig

NAME                AGE
set-max-pods        15m

Example showing a KubeletConfig machine config

$ oc get mc | grep kubelet

...
99-worker-generated-kubelet-1                  b5c5119de007945b6fe6fb215db3b8e2ceb12511   3.2.0             26m
...

The following procedure is an example to show how to configure the maximum number of pods per node on the worker nodes.

Prerequisites

  1. Obtain the label associated with the static MachineConfigPool CR for the type of node you want to configure. Perform one of the following steps:

    1. View the machine config pool: 

      $ oc describe machineconfigpool <name>

      For example: 

      $ oc describe machineconfigpool worker

      Example output

      apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfigPool
metadata:
  creationTimestamp: 2019-02-08T14:52:39Z
  generation: 1
  labels:
    custom-kubelet: set-max-pods 1

      1
      If a label has been added it appears under labels.

    2. If the label is not present, add a key/value pair: 

      $ oc label machineconfigpool worker custom-kubelet=set-max-pods

Procedure

  1. View the available machine configuration objects that you can select: 

    $ oc get machineconfig

    By default, the two kubelet-related configs are 01-master-kubelet and 01-worker-kubelet.

  2. Check the current value for the maximum pods per node: 

    $ oc describe node <node_name>

    For example: 

    $ oc describe node ci-ln-5grqprb-f76d1-ncnqq-worker-a-mdv94

    Look for value: pods: <value> in the Allocatable stanza:

    Example output

    Allocatable:
 attachable-volumes-aws-ebs:  25
 cpu:                         3500m
 hugepages-1Gi:               0
 hugepages-2Mi:               0
 memory:                      15341844Ki
 pods:                        250

  3. Set the maximum pods per node on the worker nodes by creating a custom resource file that contains the kubelet configuration:

    Important

    Kubelet configurations that target a specific machine config pool also affect any dependent pools. For example, creating a kubelet configuration for the pool containing worker nodes will also apply to any subset pools, including the pool containing infrastructure nodes. To avoid this, you must create a new machine config pool with a selection expression that only includes worker nodes, and have your kubelet configuration target this new pool. 

    apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  name: set-max-pods
spec:
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: set-max-pods 1
  kubeletConfig:
    maxPods: 500 2
    1
    Enter the label from the machine config pool.
    2
    Add the kubelet configuration. In this example, use maxPods to set the maximum pods per node.
    Note

    The rate at which the kubelet talks to the API server depends on queries per second (QPS) and burst values. The default values, 50 for kubeAPIQPS and 100 for kubeAPIBurst, are sufficient if there are limited pods running on each node. It is recommended to update the kubelet QPS and burst rates if there are enough CPU and memory resources on the node. 

    apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  name: set-max-pods
spec:
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: set-max-pods
  kubeletConfig:
    maxPods: <pod_count>
    kubeAPIBurst: <burst_rate>
    kubeAPIQPS: <QPS>

    1. Update the machine config pool for workers with the label: 

      $ oc label machineconfigpool worker custom-kubelet=set-max-pods

    2. Create the KubeletConfig object: 

      $ oc create -f change-maxPods-cr.yaml

    3. Verify that the KubeletConfig object is created: 

      $ oc get kubeletconfig

      Example output

      NAME                AGE
set-max-pods        15m

      Depending on the number of worker nodes in the cluster, wait for the worker nodes to be rebooted one by one. For a cluster with 3 worker nodes, this could take about 10 to 15 minutes.

  4. Verify that the changes are applied to the node:

    1. Check on a worker node that the maxPods value changed: 

      $ oc describe node <node_name>

    2. Locate the Allocatable stanza: 

       ...
Allocatable:
  attachable-volumes-gce-pd:  127
  cpu:                        3500m
  ephemeral-storage:          123201474766
  hugepages-1Gi:              0
  hugepages-2Mi:              0
  memory:                     14225400Ki
  pods:                       500 1
 ...
      1
      In this example, the pods parameter should report the value you set in the KubeletConfig object.

  5. Verify the change in the KubeletConfig object: 

    $ oc get kubeletconfigs set-max-pods -o yaml

    This should show a status of True and type:Success, as shown in the following example: 

    spec:
  kubeletConfig:
    maxPods: 500
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: set-max-pods
status:
  conditions:
  - lastTransitionTime: "2021-06-30T17:04:07Z"
    message: Success
    status: "True"
    type: Success

5.3.2. Creating a ContainerRuntimeConfig CR to edit CRI-O parameters

You can change some of the settings associated with the OpenShift Container Platform CRI-O runtime for the nodes associated with a specific machine config pool (MCP). Using a ContainerRuntimeConfig custom resource (CR), you set the configuration values and add a label to match the MCP. The MCO then rebuilds the crio.conf and storage.conf configuration files on the associated nodes with the updated values.

Note

To revert the changes implemented by using a ContainerRuntimeConfig CR, you must delete the CR. Removing the label from the machine config pool does not revert the changes.

You can modify the following settings by using a ContainerRuntimeConfig CR:

  • PIDs limit: Setting the PIDs limit in the ContainerRuntimeConfig is expected to be deprecated. If PIDs limits are required, it is recommended to use the podPidsLimit field in the KubeletConfig CR instead. The default podPidsLimit value is 4096 and the default pids_limit value is 0. If podPidsLimit is lower than pids_limit then the effective container PIDs limit is defined by the value set in podPidsLimit.

    Note

    The CRI-O flag is applied on the cgroup of the container, while the Kubelet flag is set on the cgroup of the pod. Please adjust the PIDs limit accordingly.

  • Log level: The logLevel parameter sets the CRI-O log_level parameter, which is the level of verbosity for log messages. The default is info (log_level = info). Other options include fatal, panic, error, warn, debug, and trace.
  • Overlay size: The overlaySize parameter sets the CRI-O Overlay storage driver size parameter, which is the maximum size of a container image.
  • Maximum log size: Setting the maximum log size in the ContainerRuntimeConfig is expected to be deprecated. If a maximum log size is required, it is recommended to use the containerLogMaxSize field in the KubeletConfig CR instead.
  • Container runtime: The defaultRuntime parameter sets the container runtime to either runc or crun. The default is runc.
Important

Support for the crun container runtime is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

You should have one ContainerRuntimeConfig CR for each machine config pool with all the config changes you want for that pool. If you are applying the same content to all the pools, you only need one ContainerRuntimeConfig CR for all the pools.

You should edit an existing ContainerRuntimeConfig CR to modify existing settings or add new settings instead of creating a new CR for each change. It is recommended to create a new ContainerRuntimeConfig CR only to modify a different machine config pool, or for changes that are intended to be temporary so that you can revert the changes.

You can create multiple ContainerRuntimeConfig CRs, as needed, with a limit of 10 per cluster. For the first ContainerRuntimeConfig CR, the MCO creates a machine config appended with containerruntime. With each subsequent CR, the controller creates a new containerruntime machine config with a numeric suffix. For example, if you have a containerruntime machine config with a -2 suffix, the next containerruntime machine config is appended with -3.

If you want to delete the machine configs, you should delete them in reverse order to avoid exceeding the limit. For example, you should delete the containerruntime-3 machine config before deleting the containerruntime-2 machine config.

Note

If you have a machine config with a containerruntime-9 suffix, and you create another ContainerRuntimeConfig CR, a new machine config is not created, even if there are fewer than 10 containerruntime machine configs.

Example showing multiple ContainerRuntimeConfig CRs

$ oc get ctrcfg

Example output

NAME         AGE
ctr-overlay  15m
ctr-level    5m45s

Example showing multiple containerruntime machine configs

$ oc get mc | grep container

Example output

...
01-master-container-runtime                        b5c5119de007945b6fe6fb215db3b8e2ceb12511   3.2.0             57m
...
01-worker-container-runtime                        b5c5119de007945b6fe6fb215db3b8e2ceb12511   3.2.0             57m
...
99-worker-generated-containerruntime               b5c5119de007945b6fe6fb215db3b8e2ceb12511   3.2.0             26m
99-worker-generated-containerruntime-1             b5c5119de007945b6fe6fb215db3b8e2ceb12511   3.2.0             17m
99-worker-generated-containerruntime-2             b5c5119de007945b6fe6fb215db3b8e2ceb12511   3.2.0             7m26s
...

The following example sets the log_level field to debug and sets the overlay size to 8 GB:

Example ContainerRuntimeConfig CR

apiVersion: machineconfiguration.openshift.io/v1
kind: ContainerRuntimeConfig
metadata:
 name: overlay-size
spec:
 machineConfigPoolSelector:
   matchLabels:
     pools.operator.machineconfiguration.openshift.io/worker: '' 1
 containerRuntimeConfig:
   logLevel: debug 2
   overlaySize: 8G 3
   defaultRuntime: "crun" 4

1
Specifies the machine config pool label. For a container runtime config, the role must match the name of the associated machine config pool.
2
Optional: Specifies the level of verbosity for log messages.
3
Optional: Specifies the maximum size of a container image.
4
Optional: Specifies the container runtime to deploy to new containers. The default value is runc.

Prerequisite

  • To enable crun, you must enable the TechPreviewNoUpgrade feature set.

    Note

    Enabling the TechPreviewNoUpgrade feature set cannot be undone and prevents minor version updates. These feature sets are not recommended on production clusters.

Procedure

To change CRI-O settings using the ContainerRuntimeConfig CR:

  1. Create a YAML file for the ContainerRuntimeConfig CR: 

    apiVersion: machineconfiguration.openshift.io/v1
kind: ContainerRuntimeConfig
metadata:
 name: overlay-size
spec:
 machineConfigPoolSelector:
   matchLabels:
     pools.operator.machineconfiguration.openshift.io/worker: '' 1
 containerRuntimeConfig: 2
   logLevel: debug
   overlaySize: 8G
    1
    Specify a label for the machine config pool that you want you want to modify.
    2
    Set the parameters as needed.

  2. Create the ContainerRuntimeConfig CR: 

    $ oc create -f <file_name>.yaml

  3. Verify that the CR is created: 

    $ oc get ContainerRuntimeConfig

    Example output

    NAME           AGE
overlay-size   3m19s

  4. Check that a new containerruntime machine config is created: 

    $ oc get machineconfigs | grep containerrun

    Example output

    99-worker-generated-containerruntime   2c9371fbb673b97a6fe8b1c52691999ed3a1bfc2  3.2.0  31s

  5. Monitor the machine config pool until all are shown as ready: 

    $ oc get mcp worker

    Example output

    NAME    CONFIG               UPDATED  UPDATING  DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT  DEGRADEDMACHINECOUNT  AGE
worker  rendered-worker-169  False    True      False     3             1                  1                    0                     9h

  6. Verify that the settings were applied in CRI-O:

    1. Open an oc debug session to a node in the machine config pool and run chroot /host. 

      $ oc debug node/<node_name>
      sh-4.4# chroot /host

    2. Verify the changes in the crio.conf file: 

      sh-4.4# crio config | grep 'log_level'

      Example output

      log_level = "debug"

    3. Verify the changes in the `storage.conf`file: 

      sh-4.4# head -n 7 /etc/containers/storage.conf

      Example output

      [storage]
  driver = "overlay"
  runroot = "/var/run/containers/storage"
  graphroot = "/var/lib/containers/storage"
  [storage.options]
    additionalimagestores = []
    size = "8G"

5.3.3. Setting the default maximum container root partition size for Overlay with CRI-O

The root partition of each container shows all of the available disk space of the underlying host. Follow this guidance to set a maximum partition size for the root disk of all containers.

To configure the maximum Overlay size, as well as other CRI-O options like the log level, you can create the following ContainerRuntimeConfig custom resource definition (CRD): 

apiVersion: machineconfiguration.openshift.io/v1
kind: ContainerRuntimeConfig
metadata:
 name: overlay-size
spec:
 machineConfigPoolSelector:
   matchLabels:
     custom-crio: overlay-size
 containerRuntimeConfig:
   logLevel: debug
   overlaySize: 8G

Procedure

  1. Create the configuration object: 

    $ oc apply -f overlaysize.yml

  2. To apply the new CRI-O configuration to your worker nodes, edit the worker machine config pool: 

    $ oc edit machineconfigpool worker

  3. Add the custom-crio label based on the matchLabels name you set in the ContainerRuntimeConfig CRD: 

    apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfigPool
metadata:
  creationTimestamp: "2020-07-09T15:46:34Z"
  generation: 3
  labels:
    custom-crio: overlay-size
    machineconfiguration.openshift.io/mco-built-in: ""

  4. Save the changes, then view the machine configs: 

    $ oc get machineconfigs

    New 99-worker-generated-containerruntime and rendered-worker-xyz objects are created:

    Example output

    99-worker-generated-containerruntime  4173030d89fbf4a7a0976d1665491a4d9a6e54f1   3.2.0             7m42s
rendered-worker-xyz                   4173030d89fbf4a7a0976d1665491a4d9a6e54f1   3.2.0             7m36s

  5. After those objects are created, monitor the machine config pool for the changes to be applied: 

    $ oc get mcp worker

    The worker nodes show UPDATING as True, as well as the number of machines, the number updated, and other details:

    Example output

    NAME   CONFIG              UPDATED   UPDATING   DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
worker rendered-worker-xyz False True False     3             2                   2                    0                      20h

    When complete, the worker nodes transition back to UPDATING as False, and the UPDATEDMACHINECOUNT number matches the MACHINECOUNT:

    Example output

    NAME   CONFIG              UPDATED   UPDATING   DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
worker   rendered-worker-xyz   True      False      False      3         3            3             0           20h

    Looking at a worker machine, you see that the new 8 GB max size configuration is applied to all of the workers:

    Example output

    head -n 7 /etc/containers/storage.conf
[storage]
  driver = "overlay"
  runroot = "/var/run/containers/storage"
  graphroot = "/var/lib/containers/storage"
  [storage.options]
    additionalimagestores = []
    size = "8G"

    Looking inside a container, you see that the root partition is now 8 GB:

    Example output

    ~ $ df -h
Filesystem                Size      Used Available Use% Mounted on
overlay                   8.0G      8.0K      8.0G   0% /

Chapter 6. Postinstallation cluster tasks

After installing OpenShift Container Platform, you can further expand and customize your cluster to your requirements.

6.1. Available cluster customizations

You complete most of the cluster configuration and customization after you deploy your OpenShift Container Platform cluster. A number of configuration resources are available.

Note

If you install your cluster on IBM Z, not all features and functions are available.

You modify the configuration resources to configure the major features of the cluster, such as the image registry, networking configuration, image build behavior, and the identity provider.

For current documentation of the settings that you control by using these resources, use the oc explain command, for example oc explain builds --api-version=config.openshift.io/v1

6.1.1. Cluster configuration resources

All cluster configuration resources are globally scoped (not namespaced) and named cluster.

Resource nameDescription

apiserver.config.openshift.io

Provides API server configuration such as certificates and certificate authorities.

authentication.config.openshift.io

Controls the identity provider and authentication configuration for the cluster.

build.config.openshift.io

Controls default and enforced configuration for all builds on the cluster.

console.config.openshift.io

Configures the behavior of the web console interface, including the logout behavior.

featuregate.config.openshift.io

Enables FeatureGates so that you can use Tech Preview features.

image.config.openshift.io

Configures how specific image registries should be treated (allowed, disallowed, insecure, CA details).

ingress.config.openshift.io

Configuration details related to routing such as the default domain for routes.

oauth.config.openshift.io

Configures identity providers and other behavior related to internal OAuth server flows.

project.config.openshift.io

Configures how projects are created including the project template.

proxy.config.openshift.io

Defines proxies to be used by components needing external network access. Note: not all components currently consume this value.

scheduler.config.openshift.io

Configures scheduler behavior such as profiles and default node selectors.

6.1.2. Operator configuration resources

These configuration resources are cluster-scoped instances, named cluster, which control the behavior of a specific component as owned by a particular Operator.

Resource nameDescription

consoles.operator.openshift.io

Controls console appearance such as branding customizations

config.imageregistry.operator.openshift.io

Configures OpenShift image registry settings such as public routing, log levels, proxy settings, resource constraints, replica counts, and storage type.

config.samples.operator.openshift.io

Configures the Samples Operator to control which example image streams and templates are installed on the cluster.

6.1.3. Additional configuration resources

These configuration resources represent a single instance of a particular component. In some cases, you can request multiple instances by creating multiple instances of the resource. In other cases, the Operator can use only a specific resource instance name in a specific namespace. Reference the component-specific documentation for details on how and when you can create additional resource instances.

Resource nameInstance nameNamespaceDescription

alertmanager.monitoring.coreos.com

main

openshift-monitoring

Controls the Alertmanager deployment parameters.

ingresscontroller.operator.openshift.io

default

openshift-ingress-operator

Configures Ingress Operator behavior such as domain, number of replicas, certificates, and controller placement.

6.1.4. Informational Resources

You use these resources to retrieve information about the cluster. Some configurations might require you to edit these resources directly.

Resource nameInstance nameDescription

clusterversion.config.openshift.io

version

In OpenShift Container Platform 4.12, you must not customize the ClusterVersion resource for production clusters. Instead, follow the process to update a cluster.

dns.config.openshift.io

cluster

You cannot modify the DNS settings for your cluster. You can view the DNS Operator status.

infrastructure.config.openshift.io

cluster

Configuration details allowing the cluster to interact with its cloud provider.

network.config.openshift.io

cluster

You cannot modify your cluster networking after installation. To customize your network, follow the process to customize networking during installation.

6.2. Adding worker nodes

After you deploy your OpenShift Container Platform cluster, you can add worker nodes to scale cluster resources. There are different ways you can add worker nodes depending on the installation method and the environment of your cluster.

6.2.1. Adding worker nodes to installer-provisioned infrastructure clusters

For installer-provisioned infrastructure clusters, you can manually or automatically scale the MachineSet object to match the number of available bare-metal hosts.

To add a bare-metal host, you must configure all network prerequisites, configure an associated baremetalhost object, then provision the worker node to the cluster. You can add a bare-metal host manually or by using the web console.

6.2.2. Adding worker nodes to user-provisioned infrastructure clusters

For user-provisioned infrastructure clusters, you can add worker nodes by using a RHEL or RHCOS ISO image and connecting it to your cluster using cluster Ignition config files. For RHEL worker nodes, the following example uses Ansible playbooks to add worker nodes to the cluster. For RHCOS worker nodes, the following example uses an ISO image and network booting to add worker nodes to the cluster.

6.2.3. Adding worker nodes to clusters managed by the Assisted Installer

For clusters managed by the Assisted Installer, you can add worker nodes by using the Red Hat OpenShift Cluster Manager console, the Assisted Installer REST API or you can manually add worker nodes using an ISO image and cluster Ignition config files.

6.2.4. Adding worker nodes to clusters managed by the multicluster engine for Kubernetes

For clusters managed by the multicluster engine for Kubernetes, you can add worker nodes by using the dedicated multicluster engine console.

6.3. Adjust worker nodes

If you incorrectly sized the worker nodes during deployment, adjust them by creating one or more new compute machine sets, scale them up, then scale the original compute machine set down before removing them.

6.3.1. Understanding the difference between compute machine sets and the machine config pool

MachineSet objects describe OpenShift Container Platform nodes with respect to the cloud or machine provider.

The MachineConfigPool object allows MachineConfigController components to define and provide the status of machines in the context of upgrades.

The MachineConfigPool object allows users to configure how upgrades are rolled out to the OpenShift Container Platform nodes in the machine config pool.

The NodeSelector object can be replaced with a reference to the MachineSet object.

6.3.2. Scaling a compute machine set manually

To add or remove an instance of a machine in a compute machine set, you can manually scale the compute machine set.

This guidance is relevant to fully automated, installer-provisioned infrastructure installations. Customized, user-provisioned infrastructure installations do not have compute machine sets.

Prerequisites

  • Install an OpenShift Container Platform cluster and the oc command line.
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. View the compute machine sets that are in the cluster by running the following command: 

    $ oc get machinesets -n openshift-machine-api

    The compute machine sets are listed in the form of <clusterid>-worker-<aws-region-az>.

  2. View the compute machines that are in the cluster by running the following command: 

    $ oc get machine -n openshift-machine-api

  3. Set the annotation on the compute machine that you want to delete by running the following command: 

    $ oc annotate machine/<machine_name> -n openshift-machine-api machine.openshift.io/delete-machine="true"

  4. Scale the compute machine set by running one of the following commands: 

    $ oc scale --replicas=2 machineset <machineset> -n openshift-machine-api

    Or: 

    $ oc edit machineset <machineset> -n openshift-machine-api
    Tip

    You can alternatively apply the following YAML to scale the compute machine set: 

    apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  name: <machineset>
  namespace: openshift-machine-api
spec:
  replicas: 2

    You can scale the compute machine set up or down. It takes several minutes for the new machines to be available.

    Important

    By default, the machine controller tries to drain the node that is backed by the machine until it succeeds. In some situations, such as with a misconfigured pod disruption budget, the drain operation might not be able to succeed. If the drain operation fails, the machine controller cannot proceed removing the machine.

    You can skip draining the node by annotating machine.openshift.io/exclude-node-draining in a specific machine.

Verification

  • Verify the deletion of the intended machine by running the following command: 

    $ oc get machines

6.3.3. The compute machine set deletion policy

Random, Newest, and Oldest are the three supported deletion options. The default is Random, meaning that random machines are chosen and deleted when scaling compute machine sets down. The deletion policy can be set according to the use case by modifying the particular compute machine set: 

spec:
  deletePolicy: <delete_policy>
  replicas: <desired_replica_count>

Specific machines can also be prioritized for deletion by adding the annotation machine.openshift.io/delete-machine=true to the machine of interest, regardless of the deletion policy.

Important

By default, the OpenShift Container Platform router pods are deployed on workers. Because the router is required to access some cluster resources, including the web console, do not scale the worker compute machine set to 0 unless you first relocate the router pods.

Note

Custom compute machine sets can be used for use cases requiring that services run on specific nodes and that those services are ignored by the controller when the worker compute machine sets are scaling down. This prevents service disruption.

6.3.4. Creating default cluster-wide node selectors

You can use default cluster-wide node selectors on pods together with labels on nodes to constrain all pods created in a cluster to specific nodes.

With cluster-wide node selectors, when you create a pod in that cluster, OpenShift Container Platform adds the default node selectors to the pod and schedules the pod on nodes with matching labels.

You configure cluster-wide node selectors by editing the Scheduler Operator custom resource (CR). You add labels to a node, a compute machine set, or a machine config. Adding the label to the compute machine set ensures that if the node or machine goes down, new nodes have the label. Labels added to a node or machine config do not persist if the node or machine goes down.

Note

You can add additional key/value pairs to a pod. But you cannot add a different value for a default key.

Procedure

To add a default cluster-wide node selector:

  1. Edit the Scheduler Operator CR to add the default cluster-wide node selectors: 

    $ oc edit scheduler cluster

    Example Scheduler Operator CR with a node selector

    apiVersion: config.openshift.io/v1
kind: Scheduler
metadata:
  name: cluster
...
spec:
  defaultNodeSelector: type=user-node,region=east 1
  mastersSchedulable: false

    1
    Add a node selector with the appropriate <key>:<value> pairs.

    After making this change, wait for the pods in the openshift-kube-apiserver project to redeploy. This can take several minutes. The default cluster-wide node selector does not take effect until the pods redeploy.

  2. Add labels to a node by using a compute machine set or editing the node directly:

    • Use a compute machine set to add labels to nodes managed by the compute machine set when a node is created:

      1. Run the following command to add labels to a MachineSet object: 

        $ oc patch MachineSet <name> --type='json' -p='[{"op":"add","path":"/spec/template/spec/metadata/labels", "value":{"<key>"="<value>","<key>"="<value>"}}]'  -n openshift-machine-api 1
        1
        Add a <key>/<value> pair for each label.

        For example: 

        $ oc patch MachineSet ci-ln-l8nry52-f76d1-hl7m7-worker-c --type='json' -p='[{"op":"add","path":"/spec/template/spec/metadata/labels", "value":{"type":"user-node","region":"east"}}]'  -n openshift-machine-api
        Tip

        You can alternatively apply the following YAML to add labels to a compute machine set: 

        apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  name: <machineset>
  namespace: openshift-machine-api
spec:
  template:
    spec:
      metadata:
        labels:
          region: "east"
          type: "user-node"

      2. Verify that the labels are added to the MachineSet object by using the oc edit command:

        For example: 

        $ oc edit MachineSet abc612-msrtw-worker-us-east-1c -n openshift-machine-api

        Example MachineSet object

        apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
  ...
spec:
  ...
  template:
    metadata:
  ...
    spec:
      metadata:
        labels:
          region: east
          type: user-node
  ...

      3. Redeploy the nodes associated with that compute machine set by scaling down to 0 and scaling up the nodes:

        For example: 

        $ oc scale --replicas=0 MachineSet ci-ln-l8nry52-f76d1-hl7m7-worker-c -n openshift-machine-api
        $ oc scale --replicas=1 MachineSet ci-ln-l8nry52-f76d1-hl7m7-worker-c -n openshift-machine-api

      4. When the nodes are ready and available, verify that the label is added to the nodes by using the oc get command: 

        $ oc get nodes -l <key>=<value>

        For example: 

        $ oc get nodes -l type=user-node

        Example output

        NAME                                       STATUS   ROLES    AGE   VERSION
ci-ln-l8nry52-f76d1-hl7m7-worker-c-vmqzp   Ready    worker   61s   v1.25.0

    • Add labels directly to a node:

      1. Edit the Node object for the node: 

        $ oc label nodes <name> <key>=<value>

        For example, to label a node: 

        $ oc label nodes ci-ln-l8nry52-f76d1-hl7m7-worker-b-tgq49 type=user-node region=east
        Tip

        You can alternatively apply the following YAML to add labels to a node: 

        kind: Node
apiVersion: v1
metadata:
  name: <node_name>
  labels:
    type: "user-node"
    region: "east"

      2. Verify that the labels are added to the node using the oc get command: 

        $ oc get nodes -l <key>=<value>,<key>=<value>

        For example: 

        $ oc get nodes -l type=user-node,region=east

        Example output

        NAME                                       STATUS   ROLES    AGE   VERSION
ci-ln-l8nry52-f76d1-hl7m7-worker-b-tgq49   Ready    worker   17m   v1.25.0

6.3.5. Creating user workloads in AWS Local Zones

After you create an Amazon Web Service (AWS) Local Zone environment, and you deploy your cluster, you can use edge worker nodes to create user workloads in Local Zone subnets.

After the openshift-installer creates the cluster, the installation program automatically specifies a taint effect of NoSchedule to each edge worker node. This means that a scheduler does not add a new pod, or deployment, to a node if the pod does not match the specified tolerations for a taint. You can modify the taint for better control over how each node creates a workload in each Local Zone subnet.

The openshift-installer creates the compute machine set manifests file with node-role.kubernetes.io/edge and node-role.kubernetes.io/worker labels applied to each edge worker node that is located in a Local Zone subnet.

Prerequisites

  • You have access to the OpenShift CLI (oc).
  • You deployed your cluster in a Virtual Private Cloud (VPC) with defined Local Zone subnets.
  • You ensured that the compute machine set for the edge workers on Local Zone subnets specifies the taints for node-role.kubernetes.io/edge.

Procedure

  1. Create a deployment resource YAML file for an example application to be deployed in the edge worker node that operates in a Local Zone subnet. Ensure that you specify the correct tolerations that match the taints for the edge worker node.

    Example of a configured deployment resource for an edge worker node that operates in a Local Zone subnet

    kind: Namespace
apiVersion: v1
metadata:
  name: <local_zone_application_namespace>
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: <pvc_name>
  namespace: <local_zone_application_namespace>
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: gp2-csi 1
  volumeMode: Filesystem
---
apiVersion: apps/v1
kind: Deployment 2
metadata:
  name: <local_zone_application> 3
  namespace: <local_zone_application_namespace> 4
spec:
  selector:
    matchLabels:
      app: <local_zone_application>
  replicas: 1
  template:
    metadata:
      labels:
        app: <local_zone_application>
        zone-group: ${ZONE_GROUP_NAME} 5
    spec:
      securityContext:
        seccompProfile:
          type: RuntimeDefault
      nodeSelector: 6
        machine.openshift.io/zone-group: ${ZONE_GROUP_NAME}
      tolerations: 7
      - key: "node-role.kubernetes.io/edge"
        operator: "Equal"
        value: ""
        effect: "NoSchedule"
      containers:
        - image: openshift/origin-node
          command:
           - "/bin/socat"
          args:
            - TCP4-LISTEN:8080,reuseaddr,fork
            - EXEC:'/bin/bash -c \"printf \\\"HTTP/1.0 200 OK\r\n\r\n\\\"; sed -e \\\"/^\r/q\\\"\"'
          imagePullPolicy: Always
          name: echoserver
          ports:
            - containerPort: 8080
          volumeMounts:
            - mountPath: "/mnt/storage"
              name: data
      volumes:
      - name: data
        persistentVolumeClaim:
          claimName: <pvc_name>

    1
    storageClassName: For the Local Zone configuration, you must specify gp2-csi.
    2
    kind: Defines the deployment resource.
    3
    name: Specifies the name of your Local Zone application. For example, local-zone-demo-app-nyc-1.
    4
    namespace: Defines the namespace for the AWS Local Zone where you want to run the user workload. For example: local-zone-app-nyc-1a.
    5
    zone-group: Defines the group to where a zone belongs. For example, us-east-1-iah-1.
    6
    nodeSelector: Targets edge worker nodes that match the specified labels.
    7
    tolerations: Sets the values that match with the taints defined on the MachineSet manifest for the Local Zone node.

  2. Create a service resource YAML file for the node. This resource exposes a pod from a targeted edge worker node to services that run inside your Local Zone network.

    Example of a configured service resource for an edge worker node that operates in a Local Zone subnet

    apiVersion: v1
kind: Service 1
metadata:
  name:  <local_zone_application>
  namespace: <local_zone_application_namespace>
spec:
  ports:
    - port: 80
      targetPort: 8080
      protocol: TCP
  type: NodePort
  selector: 2
    app: <local_zone_application>

    1
    kind: Defines the service resource.
    2
    selector: Specifies the label type applied to managed pods.

Next steps

  • Optional: Use the AWS Load Balancer (ALB) Operator to expose a pod from a targeted edge worker node to services that run inside a Local Zone subnet from a public network. See Installing the AWS Load Balancer Operator.

Additional resources

6.4. Improving cluster stability in high latency environments using worker latency profiles

If the cluster administrator has performed latency tests for platform verification, they can discover the need to adjust the operation of the cluster to ensure stability in cases of high latency. The cluster administrator need change only one parameter, recorded in a file, which controls four parameters affecting how supervisory processes read status and interpret the health of the cluster. Changing only the one parameter provides cluster tuning in an easy, supportable manner.

The Kubelet process provides the starting point for monitoring cluster health. The Kubelet sets status values for all nodes in the OpenShift Container Platform cluster. The Kubernetes Controller Manager (kube controller) reads the status values every 10 seconds, by default. If the kube controller cannot read a node status value, it loses contact with that node after a configured period. The default behavior is:

  1. The node controller on the control plane updates the node health to Unhealthy and marks the node Ready condition`Unknown`.
  2. In response, the scheduler stops scheduling pods to that node.
  3. The Node Lifecycle Controller adds a node.kubernetes.io/unreachable taint with a NoExecute effect to the node and schedules any pods on the node for eviction after five minutes, by default.

This behavior can cause problems if your network is prone to latency issues, especially if you have nodes at the network edge. In some cases, the Kubernetes Controller Manager might not receive an update from a healthy node due to network latency. The Kubelet evicts pods from the node even though the node is healthy.

To avoid this problem, you can use worker latency profiles to adjust the frequency that the Kubelet and the Kubernetes Controller Manager wait for status updates before taking action. These adjustments help to ensure that your cluster runs properly if network latency between the control plane and the worker nodes is not optimal.

These worker latency profiles contain three sets of parameters that are pre-defined with carefully tuned values to control the reaction of the cluster to increased latency. No need to experimentally find the best values manually.

You can configure worker latency profiles when installing a cluster or at any time you notice increased latency in your cluster network.

6.4.1. Understanding worker latency profiles

Worker latency profiles are four different categories of carefully-tuned parameters. The four parameters which implement these values are node-status-update-frequency, node-monitor-grace-period, default-not-ready-toleration-seconds and default-unreachable-toleration-seconds. These parameters can use values which allow you control the reaction of the cluster to latency issues without needing to determine the best values using manual methods.

Important

Setting these parameters manually is not supported. Incorrect parameter settings adversely affect cluster stability.

All worker latency profiles configure the following parameters:

node-status-update-frequency
Specifies how often the kubelet posts node status to the API server.
node-monitor-grace-period
Specifies the amount of time in seconds that the Kubernetes Controller Manager waits for an update from a kubelet before marking the node unhealthy and adding the node.kubernetes.io/not-ready or node.kubernetes.io/unreachable taint to the node.
default-not-ready-toleration-seconds
Specifies the amount of time in seconds after marking a node unhealthy that the Kube API Server Operator waits before evicting pods from that node.
default-unreachable-toleration-seconds
Specifies the amount of time in seconds after marking a node unreachable that the Kube API Server Operator waits before evicting pods from that node.

The following Operators monitor the changes to the worker latency profiles and respond accordingly:

  • The Machine Config Operator (MCO) updates the node-status-update-frequency parameter on the worker nodes.
  • The Kubernetes Controller Manager updates the node-monitor-grace-period parameter on the control plane nodes.
  • The Kubernetes API Server Operator updates the default-not-ready-toleration-seconds and default-unreachable-toleration-seconds parameters on the control plane nodes.

While the default configuration works in most cases, OpenShift Container Platform offers two other worker latency profiles for situations where the network is experiencing higher latency than usual. The three worker latency profiles are described in the following sections:

Default worker latency profile

With the Default profile, each Kubelet updates it’s status every 10 seconds (node-status-update-frequency). The Kube Controller Manager checks the statuses of Kubelet every 5 seconds (node-monitor-grace-period).

The Kubernetes Controller Manager waits 40 seconds for a status update from Kubelet before considering the Kubelet unhealthy. If no status is made available to the Kubernetes Controller Manager, it then marks the node with the node.kubernetes.io/not-ready or node.kubernetes.io/unreachable taint and evicts the pods on that node.

If a pod on that node has the NoExecute taint, the pod is run according to tolerationSeconds. If the pod has no taint, it will be evicted in 300 seconds (default-not-ready-toleration-seconds and default-unreachable-toleration-seconds settings of the Kube API Server).

ProfileComponentParameterValue

Default

kubelet

node-status-update-frequency

10s

Kubelet Controller Manager

node-monitor-grace-period

40s

Kubernetes API Server Operator

default-not-ready-toleration-seconds

300s

Kubernetes API Server Operator

default-unreachable-toleration-seconds

300s

Medium worker latency profile

Use the MediumUpdateAverageReaction profile if the network latency is slightly higher than usual.

The MediumUpdateAverageReaction profile reduces the frequency of kubelet updates to 20 seconds and changes the period that the Kubernetes Controller Manager waits for those updates to 2 minutes. The pod eviction period for a pod on that node is reduced to 60 seconds. If the pod has the tolerationSeconds parameter, the eviction waits for the period specified by that parameter.

The Kubernetes Controller Manager waits for 2 minutes to consider a node unhealthy. In another minute, the eviction process starts.

ProfileComponentParameterValue

MediumUpdateAverageReaction

kubelet

node-status-update-frequency

20s

Kubelet Controller Manager

node-monitor-grace-period

2m

Kubernetes API Server Operator

default-not-ready-toleration-seconds

60s

Kubernetes API Server Operator

default-unreachable-toleration-seconds

60s

Low worker latency profile

Use the LowUpdateSlowReaction profile if the network latency is extremely high.

The LowUpdateSlowReaction profile reduces the frequency of kubelet updates to 1 minute and changes the period that the Kubernetes Controller Manager waits for those updates to 5 minutes. The pod eviction period for a pod on that node is reduced to 60 seconds. If the pod has the tolerationSeconds parameter, the eviction waits for the period specified by that parameter.

The Kubernetes Controller Manager waits for 5 minutes to consider a node unhealthy. In another minute, the eviction process starts.

ProfileComponentParameterValue

LowUpdateSlowReaction

kubelet

node-status-update-frequency

1m

Kubelet Controller Manager

node-monitor-grace-period

5m

Kubernetes API Server Operator

default-not-ready-toleration-seconds

60s

Kubernetes API Server Operator

default-unreachable-toleration-seconds

60s

6.4.2. Using and changing worker latency profiles

To change a worker latency profile to deal with network latency, edit the node.config object to add the name of the profile. You can change the profile at any time as latency increases or decreases.

You must move one worker latency profile at a time. For example, you cannot move directly from the Default profile to the LowUpdateSlowReaction worker latency profile. You must move from the Default worker latency profile to the MediumUpdateAverageReaction profile first, then to LowUpdateSlowReaction. Similarly, when returning to the Default profile, you must move from the low profile to the medium profile first, then to Default.

Note

You can also configure worker latency profiles upon installing an OpenShift Container Platform cluster.

Procedure

To move from the default worker latency profile:

  1. Move to the medium worker latency profile:

    1. Edit the node.config object: 

      $ oc edit nodes.config/cluster

    2. Add spec.workerLatencyProfile: MediumUpdateAverageReaction:

      Example node.config object

      apiVersion: config.openshift.io/v1
kind: Node
metadata:
  annotations:
    include.release.openshift.io/ibm-cloud-managed: "true"
    include.release.openshift.io/self-managed-high-availability: "true"
    include.release.openshift.io/single-node-developer: "true"
    release.openshift.io/create-only: "true"
  creationTimestamp: "2022-07-08T16:02:51Z"
  generation: 1
  name: cluster
  ownerReferences:
  - apiVersion: config.openshift.io/v1
    kind: ClusterVersion
    name: version
    uid: 36282574-bf9f-409e-a6cd-3032939293eb
  resourceVersion: "1865"
  uid: 0c0f7a4c-4307-4187-b591-6155695ac85b
spec:
  workerLatencyProfile: MediumUpdateAverageReaction 1

# ...

      1
      Specifies the medium worker latency policy.

      Scheduling on each worker node is disabled as the change is being applied.

  2. Optional: Move to the low worker latency profile:

    1. Edit the node.config object: 

      $ oc edit nodes.config/cluster

    2. Change the spec.workerLatencyProfile value to LowUpdateSlowReaction:

      Example node.config object

      apiVersion: config.openshift.io/v1
kind: Node
metadata:
  annotations:
    include.release.openshift.io/ibm-cloud-managed: "true"
    include.release.openshift.io/self-managed-high-availability: "true"
    include.release.openshift.io/single-node-developer: "true"
    release.openshift.io/create-only: "true"
  creationTimestamp: "2022-07-08T16:02:51Z"
  generation: 1
  name: cluster
  ownerReferences:
  - apiVersion: config.openshift.io/v1
    kind: ClusterVersion
    name: version
    uid: 36282574-bf9f-409e-a6cd-3032939293eb
  resourceVersion: "1865"
  uid: 0c0f7a4c-4307-4187-b591-6155695ac85b
spec:
  workerLatencyProfile: LowUpdateSlowReaction 1

# ...

      1
      Specifies use of the low worker latency policy.

Scheduling on each worker node is disabled as the change is being applied.

Verification

  • When all nodes return to the Ready condition, you can use the following command to look in the Kubernetes Controller Manager to ensure it was applied: 

    $ oc get KubeControllerManager -o yaml | grep -i workerlatency -A 5 -B 5

    Example output

    # ...
    - lastTransitionTime: "2022-07-11T19:47:10Z"
      reason: ProfileUpdated
      status: "False"
      type: WorkerLatencyProfileProgressing
    - lastTransitionTime: "2022-07-11T19:47:10Z" 1
      message: all static pod revision(s) have updated latency profile
      reason: ProfileUpdated
      status: "True"
      type: WorkerLatencyProfileComplete
    - lastTransitionTime: "2022-07-11T19:20:11Z"
      reason: AsExpected
      status: "False"
      type: WorkerLatencyProfileDegraded
    - lastTransitionTime: "2022-07-11T19:20:36Z"
      status: "False"
# ...

    1
    Specifies that the profile is applied and active.

To change the medium profile to default or change the default to medium, edit the node.config object and set the spec.workerLatencyProfile parameter to the appropriate value.

6.5. Managing control plane machines

Control plane machine sets provide management capabilities for control plane machines that are similar to what compute machine sets provide for compute machines. The availability and initial status of control plane machine sets on your cluster depend on your cloud provider and the version of OpenShift Container Platform that you installed. For more information, see Getting started with control plane machine sets.

6.6. Creating infrastructure machine sets for production environments

You can create a compute machine set to create machines that host only infrastructure components, such as the default router, the integrated container image registry, and components for cluster metrics and monitoring. These infrastructure machines are not counted toward the total number of subscriptions that are required to run the environment.

In a production deployment, it is recommended that you deploy at least three compute machine sets to hold infrastructure components. Both OpenShift Logging and Red Hat OpenShift Service Mesh deploy Elasticsearch, which requires three instances to be installed on different nodes. Each of these nodes can be deployed to different availability zones for high availability. A configuration like this requires three different compute machine sets, one for each availability zone. In global Azure regions that do not have multiple availability zones, you can use availability sets to ensure high availability.

For information on infrastructure nodes and which components can run on infrastructure nodes, see Creating infrastructure machine sets.

To create an infrastructure node, you can use a machine set, assign a label to the nodes, or use a machine config pool.

For sample machine sets that you can use with these procedures, see Creating machine sets for different clouds.

Applying a specific node selector to all infrastructure components causes OpenShift Container Platform to schedule those workloads on nodes with that label.

6.6.1. Creating a compute machine set

In addition to the compute machine sets created by the installation program, you can create your own to dynamically manage the machine compute resources for specific workloads of your choice.

Prerequisites

  • Deploy an OpenShift Container Platform cluster.
  • Install the OpenShift CLI (oc).
  • Log in to oc as a user with cluster-admin permission.

Procedure

  1. Create a new YAML file that contains the compute machine set custom resource (CR) sample and is named <file_name>.yaml.

    Ensure that you set the <clusterID> and <role> parameter values.

  2. Optional: If you are not sure which value to set for a specific field, you can check an existing compute machine set from your cluster.

    1. To list the compute machine sets in your cluster, run the following command: 

      $ oc get machinesets -n openshift-machine-api

      Example output

      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
agl030519-vplxk-worker-us-east-1d   0         0                             55m
agl030519-vplxk-worker-us-east-1e   0         0                             55m
agl030519-vplxk-worker-us-east-1f   0         0                             55m

    2. To view values of a specific compute machine set custom resource (CR), run the following command: 

      $ oc get machineset <machineset_name> \
  -n openshift-machine-api -o yaml

      Example output

      apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> 1
  name: <infrastructure_id>-<role> 2
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
        machine.openshift.io/cluster-api-machine-role: <role>
        machine.openshift.io/cluster-api-machine-type: <role>
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-<role>
    spec:
      providerSpec: 3
        ...

      1
      The cluster infrastructure ID.
      2
      A default node label.
      Note

      For clusters that have user-provisioned infrastructure, a compute machine set can only create worker and infra type machines.

      3
      The values in the <providerSpec> section of the compute machine set CR are platform-specific. For more information about <providerSpec> parameters in the CR, see the sample compute machine set CR configuration for your provider.

  3. Create a MachineSet CR by running the following command: 

    $ oc create -f <file_name>.yaml

Verification

  • View the list of compute machine sets by running the following command: 

    $ oc get machineset -n openshift-machine-api

    Example output

    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
agl030519-vplxk-infra-us-east-1a    1         1         1       1           11m
agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
agl030519-vplxk-worker-us-east-1d   0         0                             55m
agl030519-vplxk-worker-us-east-1e   0         0                             55m
agl030519-vplxk-worker-us-east-1f   0         0                             55m

    When the new compute machine set is available, the DESIRED and CURRENT values match. If the compute machine set is not available, wait a few minutes and run the command again.

6.6.2. Creating an infrastructure node

Important

See Creating infrastructure machine sets for installer-provisioned infrastructure environments or for any cluster where the control plane nodes are managed by the machine API.

Requirements of the cluster dictate that infrastructure, also called infra nodes, be provisioned. The installer only provides provisions for control plane and worker nodes. Worker nodes can be designated as infrastructure nodes or application, also called app, nodes through labeling.

Procedure

  1. Add a label to the worker node that you want to act as application node: 

    $ oc label node <node-name> node-role.kubernetes.io/app=""

  2. Add a label to the worker nodes that you want to act as infrastructure nodes: 

    $ oc label node <node-name> node-role.kubernetes.io/infra=""

  3. Check to see if applicable nodes now have the infra role and app roles: 

    $ oc get nodes

  4. Create a default cluster-wide node selector. The default node selector is applied to pods created in all namespaces. This creates an intersection with any existing node selectors on a pod, which additionally constrains the pod’s selector.

    Important

    If the default node selector key conflicts with the key of a pod’s label, then the default node selector is not applied.

    However, do not set a default node selector that might cause a pod to become unschedulable. For example, setting the default node selector to a specific node role, such as node-role.kubernetes.io/infra="", when a pod’s label is set to a different node role, such as node-role.kubernetes.io/master="", can cause the pod to become unschedulable. For this reason, use caution when setting the default node selector to specific node roles.

    You can alternatively use a project node selector to avoid cluster-wide node selector key conflicts.

    1. Edit the Scheduler object: 

      $ oc edit scheduler cluster

    2. Add the defaultNodeSelector field with the appropriate node selector: 

      apiVersion: config.openshift.io/v1
kind: Scheduler
metadata:
  name: cluster
spec:
  defaultNodeSelector: node-role.kubernetes.io/infra="" 1
# ...
      1
      This example node selector deploys pods on infrastructure nodes by default.
    3. Save the file to apply the changes.

You can now move infrastructure resources to the newly labeled infra nodes.

Additional resources

  • For information on how to configure project node selectors to avoid cluster-wide node selector key conflicts, see Project node selectors.

6.6.3. Creating a machine config pool for infrastructure machines

If you need infrastructure machines to have dedicated configurations, you must create an infra pool.

Procedure

  1. Add a label to the node you want to assign as the infra node with a specific label: 

    $ oc label node <node_name> <label>
    $ oc label node ci-ln-n8mqwr2-f76d1-xscn2-worker-c-6fmtx node-role.kubernetes.io/infra=

  2. Create a machine config pool that contains both the worker role and your custom role as machine config selector: 

    $ cat infra.mcp.yaml

    Example output

    apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfigPool
metadata:
  name: infra
spec:
  machineConfigSelector:
    matchExpressions:
      - {key: machineconfiguration.openshift.io/role, operator: In, values: [worker,infra]} 1
  nodeSelector:
    matchLabels:
      node-role.kubernetes.io/infra: "" 2

    1
    Add the worker role and your custom role.
    2
    Add the label you added to the node as a nodeSelector.
    Note

    Custom machine config pools inherit machine configs from the worker pool. Custom pools use any machine config targeted for the worker pool, but add the ability to also deploy changes that are targeted at only the custom pool. Because a custom pool inherits resources from the worker pool, any change to the worker pool also affects the custom pool.

  3. After you have the YAML file, you can create the machine config pool: 

    $ oc create -f infra.mcp.yaml

  4. Check the machine configs to ensure that the infrastructure configuration rendered successfully: 

    $ oc get machineconfig

    Example output

    NAME                                                        GENERATEDBYCONTROLLER                      IGNITIONVERSION   CREATED
00-master                                                   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
00-worker                                                   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
01-master-container-runtime                                 365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
01-master-kubelet                                           365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
01-worker-container-runtime                                 365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
01-worker-kubelet                                           365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
99-master-1ae2a1e0-a115-11e9-8f14-005056899d54-registries   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
99-master-ssh                                                                                          3.2.0             31d
99-worker-1ae64748-a115-11e9-8f14-005056899d54-registries   365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             31d
99-worker-ssh                                                                                          3.2.0             31d
rendered-infra-4e48906dca84ee702959c71a53ee80e7             365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             23m
rendered-master-072d4b2da7f88162636902b074e9e28e            5b6fb8349a29735e48446d435962dec4547d3090   3.2.0             31d
rendered-master-3e88ec72aed3886dec061df60d16d1af            02c07496ba0417b3e12b78fb32baf6293d314f79   3.2.0             31d
rendered-master-419bee7de96134963a15fdf9dd473b25            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             17d
rendered-master-53f5c91c7661708adce18739cc0f40fb            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             13d
rendered-master-a6a357ec18e5bce7f5ac426fc7c5ffcd            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             7d3h
rendered-master-dc7f874ec77fc4b969674204332da037            5b6fb8349a29735e48446d435962dec4547d3090   3.2.0             31d
rendered-worker-1a75960c52ad18ff5dfa6674eb7e533d            5b6fb8349a29735e48446d435962dec4547d3090   3.2.0             31d
rendered-worker-2640531be11ba43c61d72e82dc634ce6            5b6fb8349a29735e48446d435962dec4547d3090   3.2.0             31d
rendered-worker-4e48906dca84ee702959c71a53ee80e7            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             7d3h
rendered-worker-4f110718fe88e5f349987854a1147755            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             17d
rendered-worker-afc758e194d6188677eb837842d3b379            02c07496ba0417b3e12b78fb32baf6293d314f79   3.2.0             31d
rendered-worker-daa08cc1e8f5fcdeba24de60cd955cc3            365c1cfd14de5b0e3b85e0fc815b0060f36ab955   3.2.0             13d

    You should see a new machine config, with the rendered-infra-* prefix.

  5. Optional: To deploy changes to a custom pool, create a machine config that uses the custom pool name as the label, such as infra. Note that this is not required and only shown for instructional purposes. In this manner, you can apply any custom configurations specific to only your infra nodes.

    Note

    After you create the new machine config pool, the MCO generates a new rendered config for that pool, and associated nodes of that pool reboot to apply the new configuration.

    1. Create a machine config: 

      $ cat infra.mc.yaml

      Example output

      apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  name: 51-infra
  labels:
    machineconfiguration.openshift.io/role: infra 1
spec:
  config:
    ignition:
      version: 3.2.0
    storage:
      files:
      - path: /etc/infratest
        mode: 0644
        contents:
          source: data:,infra

      1
      Add the label you added to the node as a nodeSelector.

    2. Apply the machine config to the infra-labeled nodes: 

      $ oc create -f infra.mc.yaml

  6. Confirm that your new machine config pool is available: 

    $ oc get mcp

    Example output

    NAME     CONFIG                                             UPDATED   UPDATING   DEGRADED   MACHINECOUNT   READYMACHINECOUNT   UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
infra    rendered-infra-60e35c2e99f42d976e084fa94da4d0fc    True      False      False      1              1                   1                     0                      4m20s
master   rendered-master-9360fdb895d4c131c7c4bebbae099c90   True      False      False      3              3                   3                     0                      91m
worker   rendered-worker-60e35c2e99f42d976e084fa94da4d0fc   True      False      False      2              2                   2                     0                      91m

    In this example, a worker node was changed to an infra node.

Additional resources

6.7. Assigning machine set resources to infrastructure nodes

After creating an infrastructure machine set, the worker and infra roles are applied to new infra nodes. Nodes with the infra role are not counted toward the total number of subscriptions that are required to run the environment, even when the worker role is also applied.

However, when an infra node is assigned the worker role, there is a chance that user workloads can get assigned inadvertently to the infra node. To avoid this, you can apply a taint to the infra node and tolerations for the pods that you want to control.

6.7.1. Binding infrastructure node workloads using taints and tolerations

If you have an infra node that has the infra and worker roles assigned, you must configure the node so that user workloads are not assigned to it.

Important

It is recommended that you preserve the dual infra,worker label that is created for infra nodes and use taints and tolerations to manage nodes that user workloads are scheduled on. If you remove the worker label from the node, you must create a custom pool to manage it. A node with a label other than master or worker is not recognized by the MCO without a custom pool. Maintaining the worker label allows the node to be managed by the default worker machine config pool, if no custom pools that select the custom label exists. The infra label communicates to the cluster that it does not count toward the total number of subscriptions.

Prerequisites

  • Configure additional MachineSet objects in your OpenShift Container Platform cluster.

Procedure

  1. Add a taint to the infra node to prevent scheduling user workloads on it:

    1. Determine if the node has the taint: 

      $ oc describe nodes <node_name>

      Sample output

      oc describe node ci-ln-iyhx092-f76d1-nvdfm-worker-b-wln2l
Name:               ci-ln-iyhx092-f76d1-nvdfm-worker-b-wln2l
Roles:              worker
 ...
Taints:             node-role.kubernetes.io/infra:NoSchedule
 ...

      This example shows that the node has a taint. You can proceed with adding a toleration to your pod in the next step.

    2. If you have not configured a taint to prevent scheduling user workloads on it: 

      $ oc adm taint nodes <node_name> <key>=<value>:<effect>

      For example: 

      $ oc adm taint nodes node1 node-role.kubernetes.io/infra=reserved:NoExecute
      Tip

      You can alternatively apply the following YAML to add the taint: 

      kind: Node
apiVersion: v1
metadata:
  name: <node_name>
  labels:
    ...
spec:
  taints:
    - key: node-role.kubernetes.io/infra
      effect: NoExecute
      value: reserved
  ...

      This example places a taint on node1 that has key node-role.kubernetes.io/infra and taint effect NoSchedule. Nodes with the NoSchedule effect schedule only pods that tolerate the taint, but allow existing pods to remain scheduled on the node.

      Note

      If a descheduler is used, pods violating node taints could be evicted from the cluster.

  2. Add tolerations for the pod configurations you want to schedule on the infra node, like router, registry, and monitoring workloads. Add the following code to the Pod object specification: 

    tolerations:
  - effect: NoExecute 1
    key: node-role.kubernetes.io/infra 2
    operator: Exists 3
    value: reserved 4
    1
    Specify the effect that you added to the node.
    2
    Specify the key that you added to the node.
    3
    Specify the Exists Operator to require a taint with the key node-role.kubernetes.io/infra to be present on the node.
    4
    Specify the value of the key-value pair taint that you added to the node.

    This toleration matches the taint created by the oc adm taint command. A pod with this toleration can be scheduled onto the infra node.

    Note

    Moving pods for an Operator installed via OLM to an infra node is not always possible. The capability to move Operator pods depends on the configuration of each Operator.

  3. Schedule the pod to the infra node using a scheduler. See the documentation for Controlling pod placement onto nodes for details.

Additional resources

6.8. Moving resources to infrastructure machine sets

Some of the infrastructure resources are deployed in your cluster by default. You can move them to the infrastructure machine sets that you created.

6.8.1. Moving the router

You can deploy the router pod to a different compute machine set. By default, the pod is deployed to a worker node.

Prerequisites

  • Configure additional compute machine sets in your OpenShift Container Platform cluster.

Procedure

  1. View the IngressController custom resource for the router Operator: 

    $ oc get ingresscontroller default -n openshift-ingress-operator -o yaml

    The command output resembles the following text: 

    apiVersion: operator.openshift.io/v1
kind: IngressController
metadata:
  creationTimestamp: 2019-04-18T12:35:39Z
  finalizers:
  - ingresscontroller.operator.openshift.io/finalizer-ingresscontroller
  generation: 1
  name: default
  namespace: openshift-ingress-operator
  resourceVersion: "11341"
  selfLink: /apis/operator.openshift.io/v1/namespaces/openshift-ingress-operator/ingresscontrollers/default
  uid: 79509e05-61d6-11e9-bc55-02ce4781844a
spec: {}
status:
  availableReplicas: 2
  conditions:
  - lastTransitionTime: 2019-04-18T12:36:15Z
    status: "True"
    type: Available
  domain: apps.<cluster>.example.com
  endpointPublishingStrategy:
    type: LoadBalancerService
  selector: ingresscontroller.operator.openshift.io/deployment-ingresscontroller=default

  2. Edit the ingresscontroller resource and change the nodeSelector to use the infra label: 

    $ oc edit ingresscontroller default -n openshift-ingress-operator
      spec:
    nodePlacement:
      nodeSelector: 1
        matchLabels:
          node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    1
    Add a nodeSelector parameter with the appropriate value to the component you want to move. You can use a nodeSelector in the format shown or use <key>: <value> pairs, based on the value specified for the node. If you added a taint to the infrastructure node, also add a matching toleration.

  3. Confirm that the router pod is running on the infra node.

    1. View the list of router pods and note the node name of the running pod: 

      $ oc get pod -n openshift-ingress -o wide

      Example output

      NAME                              READY     STATUS        RESTARTS   AGE       IP           NODE                           NOMINATED NODE   READINESS GATES
router-default-86798b4b5d-bdlvd   1/1      Running       0          28s       10.130.2.4   ip-10-0-217-226.ec2.internal   <none>           <none>
router-default-955d875f4-255g8    0/1      Terminating   0          19h       10.129.2.4   ip-10-0-148-172.ec2.internal   <none>           <none>

      In this example, the running pod is on the ip-10-0-217-226.ec2.internal node.

    2. View the node status of the running pod: 

      $ oc get node <node_name> 1
      1
      Specify the <node_name> that you obtained from the pod list.

      Example output

      NAME                          STATUS  ROLES         AGE   VERSION
ip-10-0-217-226.ec2.internal  Ready   infra,worker  17h   v1.25.0

      Because the role list includes infra, the pod is running on the correct node.

6.8.2. Moving the default registry

You configure the registry Operator to deploy its pods to different nodes.

Prerequisites

  • Configure additional compute machine sets in your OpenShift Container Platform cluster.

Procedure

  1. View the config/instance object: 

    $ oc get configs.imageregistry.operator.openshift.io/cluster -o yaml

    Example output

    apiVersion: imageregistry.operator.openshift.io/v1
kind: Config
metadata:
  creationTimestamp: 2019-02-05T13:52:05Z
  finalizers:
  - imageregistry.operator.openshift.io/finalizer
  generation: 1
  name: cluster
  resourceVersion: "56174"
  selfLink: /apis/imageregistry.operator.openshift.io/v1/configs/cluster
  uid: 36fd3724-294d-11e9-a524-12ffeee2931b
spec:
  httpSecret: d9a012ccd117b1e6616ceccb2c3bb66a5fed1b5e481623
  logging: 2
  managementState: Managed
  proxy: {}
  replicas: 1
  requests:
    read: {}
    write: {}
  storage:
    s3:
      bucket: image-registry-us-east-1-c92e88cad85b48ec8b312344dff03c82-392c
      region: us-east-1
status:
...

  2. Edit the config/instance object: 

    $ oc edit configs.imageregistry.operator.openshift.io/cluster
    spec:
  affinity:
    podAntiAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - podAffinityTerm:
          namespaces:
          - openshift-image-registry
          topologyKey: kubernetes.io/hostname
        weight: 100
  logLevel: Normal
  managementState: Managed
  nodeSelector: 1
    node-role.kubernetes.io/infra: ""
  tolerations:
  - effect: NoSchedule
    key: node-role.kubernetes.io/infra
    value: reserved
  - effect: NoExecute
    key: node-role.kubernetes.io/infra
    value: reserved
    1
    Add a nodeSelector parameter with the appropriate value to the component you want to move. You can use a nodeSelector in the format shown or use <key>: <value> pairs, based on the value specified for the node. If you added a taint to the infrasructure node, also add a matching toleration.

  3. Verify the registry pod has been moved to the infrastructure node.

    1. Run the following command to identify the node where the registry pod is located: 

      $ oc get pods -o wide -n openshift-image-registry

    2. Confirm the node has the label you specified: 

      $ oc describe node <node_name>

      Review the command output and confirm that node-role.kubernetes.io/infra is in the LABELS list.

6.8.3. Moving the monitoring solution

The monitoring stack includes multiple components, including Prometheus, Thanos Querier, and Alertmanager. The Cluster Monitoring Operator manages this stack. To redeploy the monitoring stack to infrastructure nodes, you can create and apply a custom config map.

Procedure

  1. Edit the cluster-monitoring-config config map and change the nodeSelector to use the infra label: 

    $ oc edit configmap cluster-monitoring-config -n openshift-monitoring
    apiVersion: v1
kind: ConfigMap
metadata:
  name: cluster-monitoring-config
  namespace: openshift-monitoring
data:
  config.yaml: |+
    alertmanagerMain:
      nodeSelector: 1
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    prometheusK8s:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    prometheusOperator:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    k8sPrometheusAdapter:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    kubeStateMetrics:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    telemeterClient:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    openshiftStateMetrics:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    thanosQuerier:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoSchedule
      - key: node-role.kubernetes.io/infra
        value: reserved
        effect: NoExecute
    1
    Add a nodeSelector parameter with the appropriate value to the component you want to move. You can use a nodeSelector in the format shown or use <key>: <value> pairs, based on the value specified for the node. If you added a taint to the infrasructure node, also add a matching toleration.

  2. Watch the monitoring pods move to the new machines: 

    $ watch 'oc get pod -n openshift-monitoring -o wide'

  3. If a component has not moved to the infra node, delete the pod with this component: 

    $ oc delete pod -n openshift-monitoring <pod>

    The component from the deleted pod is re-created on the infra node.

6.8.4. Moving logging resources

For information about moving logging resources, see:

6.9. Applying autoscaling to your cluster

Applying autoscaling to an OpenShift Container Platform cluster involves deploying a cluster autoscaler and then deploying machine autoscalers for each machine type in your cluster.

For more information, see Applying autoscaling to an OpenShift Container Platform cluster.

6.10. Configuring Linux cgroup v2

You can enable Linux control group version 2 (cgroup v2) in your cluster by editing the node.config object. Enabling cgroup v2 in OpenShift Container Platform disables all cgroups version 1 controllers and hierarchies in your cluster. cgroup v1 is enabled by default.

cgroup v2 is the current version of the Linux cgroup API. cgroup v2 offers several improvements over cgroup v1, including a unified hierarchy, safer sub-tree delegation, new features such as Pressure Stall Information, and enhanced resource management and isolation. However, cgroup v2 has different CPU, memory, and I/O management characteristics than cgroup v1. Therefore, some workloads might experience slight differences in memory or CPU usage on clusters that run cgroup v2.

Important

OpenShift Container Platform cgroups version 2 support is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

Note

Currently, disabling CPU load balancing is not supported by cgroup v2. As a result, you might not get the desired behavior from performance profiles if you have cgroup v2 enabled. Enabling cgroup v2 is not recommended if you are using performance profiles.

Prerequisites

  • You have a running OpenShift Container Platform cluster that uses version 4.12 or later.
  • You are logged in to the cluster as a user with administrative privileges.
  • You have enabled the TechPreviewNoUpgrade feature set by using the feature gates.

Procedure

  1. Enable cgroup v2 on nodes:

    1. Edit the node.config object: 

      $ oc edit nodes.config/cluster

    2. Add spec.cgroupMode: "v2":

      Example node.config object

      apiVersion: config.openshift.io/v1
kind: Node
metadata:
  annotations:
    include.release.openshift.io/ibm-cloud-managed: "true"
    include.release.openshift.io/self-managed-high-availability: "true"
    include.release.openshift.io/single-node-developer: "true"
    release.openshift.io/create-only: "true"
  creationTimestamp: "2022-07-08T16:02:51Z"
  generation: 1
  name: cluster
  ownerReferences:
  - apiVersion: config.openshift.io/v1
    kind: ClusterVersion
    name: version
    uid: 36282574-bf9f-409e-a6cd-3032939293eb
  resourceVersion: "1865"
  uid: 0c0f7a4c-4307-4187-b591-6155695ac85b
spec:
  cgroupMode: "v2" 1
...

      1
      Enables cgroup v2.

Verification

  1. Check the machine configs to see that the new machine configs were added: 

    $ oc get mc

    Example output

    NAME                                               GENERATEDBYCONTROLLER                      IGNITIONVERSION   AGE
00-master                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
00-worker                                          52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-master-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-container-runtime                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
01-worker-kubelet                                  52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
97-master-generated-kubelet                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0              3m 1
99-worker-generated-kubelet                        52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0              3m
99-master-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-master-ssh                                                                                 3.2.0             40m
99-worker-generated-registries                     52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
99-worker-ssh                                                                                 3.2.0             40m
rendered-master-23e785de7587df95a4b517e0647e5ab7   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
rendered-worker-5d596d9293ca3ea80c896a1191735bb1   52dd3ba6a9a527fc3ab42afac8d12b693534c8c9   3.2.0             33m
worker-enable-cgroups-v2                                                                      3.2.0             10s

    1
    New machine configs are created, as expected.

  2. Check that the new kernelArguments were added to the new machine configs: 

    $ oc describe mc <name>

    Example output

    apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 05-worker-kernelarg-selinuxpermissive
spec:
  kernelArguments:
  - systemd_unified_cgroup_hierarchy=1 1
  - cgroup_no_v1="all" 2
  - psi=1 3

    1
    Enables cgroup v2 in systemd.
    2
    Disables cgroups v1.
    3
    Enables the Linux Pressure Stall Information (PSI) feature.

  3. Check the nodes to see that scheduling on the nodes is disabled. This indicates that the change is being applied: 

    $ oc get nodes

    Example output

    NAME                                       STATUS                     ROLES    AGE   VERSION
ci-ln-fm1qnwt-72292-99kt6-master-0         Ready                      master   58m   v1.25.0
ci-ln-fm1qnwt-72292-99kt6-master-1         Ready                      master   58m   v1.25.0
ci-ln-fm1qnwt-72292-99kt6-master-2         Ready                      master   58m   v1.25.0
ci-ln-fm1qnwt-72292-99kt6-worker-a-h5gt4   Ready,SchedulingDisabled   worker   48m   v1.25.0
ci-ln-fm1qnwt-72292-99kt6-worker-b-7vtmd   Ready                      worker   48m   v1.25.0
ci-ln-fm1qnwt-72292-99kt6-worker-c-rhzkv   Ready                      worker   48m   v1.25.0

  4. After a node returns to the Ready state, start a debug session for that node: 

    $ oc debug node/<node_name>

  5. Set /host as the root directory within the debug shell: 

    sh-4.4# chroot /host

  6. Check that the sys/fs/cgroup/cgroup2fs file is present on your nodes. This file is created by cgroup v2: 

    $ stat -c %T -f /sys/fs/cgroup

    Example output

    cgroup2fs

6.11. Enabling Technology Preview features using FeatureGates

You can turn on a subset of the current Technology Preview features on for all nodes in the cluster by editing the FeatureGate custom resource (CR).

6.11.1. Understanding feature gates

You can use the FeatureGate custom resource (CR) to enable specific feature sets in your cluster. A feature set is a collection of OpenShift Container Platform features that are not enabled by default.

You can activate the following feature set by using the FeatureGate CR:

  • TechPreviewNoUpgrade. This feature set is a subset of the current Technology Preview features. This feature set allows you to enable these Technology Preview features on test clusters, where you can fully test them, while leaving the features disabled on production clusters.

    Warning

    Enabling the TechPreviewNoUpgrade feature set on your cluster cannot be undone and prevents minor version updates. You should not enable this feature set on production clusters.

    The following Technology Preview features are enabled by this feature set:

    • CSI automatic migration. Enables automatic migration for supported in-tree volume plugins to their equivalent Container Storage Interface (CSI) drivers. Supported for:

      • Azure File (CSIMigrationAzureFile)
      • VMware vSphere (CSIMigrationvSphere)
    • Shared Resources CSI Driver and Build CSI Volumes in OpenShift Builds. Enables the Container Storage Interface (CSI). (CSIDriverSharedResource)
    • CSI volumes. Enables CSI volume support for the OpenShift Container Platform build system. (BuildCSIVolumes)
    • Swap memory on nodes. Enables swap memory use for OpenShift Container Platform workloads on a per-node basis. (NodeSwap)
    • cgroups v2. Enables cgroup v2, the next version of the Linux cgroup API. (CGroupsV2)
    • crun. Enables the crun container runtime. (Crun)
    • Insights Operator. Enables the Insights Operator, which gathers OpenShift Container Platform configuration data and sends it to Red Hat. (InsightsConfigAPI)
    • External cloud providers. Enables support for external cloud providers for clusters on vSphere, AWS, Azure, and GCP. Support for OpenStack is GA. (ExternalCloudProvider)
    • Pod topology spread constraints. Enables the matchLabelKeys parameter for pod topology constraints. The parameter is list of pod label keys to select the pods over which spreading will be calculated. (MatchLabelKeysInPodTopologySpread)

    • Pod security admission enforcement. Enables restricted enforcement for pod security admission. Instead of only logging a warning, pods are rejected if they violate pod security standards. (OpenShiftPodSecurityAdmission)

      Note

      Pod security admission restricted enforcement is only activated if you enable the TechPreviewNoUpgrade feature set after your OpenShift Container Platform cluster is installed. It is not activated if you enable the TechPreviewNoUpgrade feature set during cluster installation.

6.11.2. Enabling feature sets using the web console

You can use the OpenShift Container Platform web console to enable feature sets for all of the nodes in a cluster by editing the FeatureGate custom resource (CR).

Procedure

To enable feature sets:

  1. In the OpenShift Container Platform web console, switch to the Administration → Custom Resource Definitions page.
  2. On the Custom Resource Definitions page, click FeatureGate.
  3. On the Custom Resource Definition Details page, click the Instances tab.
  4. Click the cluster feature gate, then click the YAML tab.

  5. Edit the cluster instance to add specific feature sets:

    Warning

    Enabling the TechPreviewNoUpgrade feature set on your cluster cannot be undone and prevents minor version updates. You should not enable this feature set on production clusters.

    Sample Feature Gate custom resource

    apiVersion: config.openshift.io/v1
kind: FeatureGate
metadata:
  name: cluster 1
# ...
spec:
  featureSet: TechPreviewNoUpgrade 2

    1
    The name of the FeatureGate CR must be cluster.
    2
    Add the feature set that you want to enable:
    • TechPreviewNoUpgrade enables specific Technology Preview features.

    After you save the changes, new machine configs are created, the machine config pools are updated, and scheduling on each node is disabled while the change is being applied.

Verification

You can verify that the feature gates are enabled by looking at the kubelet.conf file on a node after the nodes return to the ready state.

  1. From the Administrator perspective in the web console, navigate to Compute → Nodes.
  2. Select a node.
  3. In the Node details page, click Terminal.

  4. In the terminal window, change your root directory to /host: 

    sh-4.2# chroot /host

  5. View the kubelet.conf file: 

    sh-4.2# cat /etc/kubernetes/kubelet.conf

    Sample output

    # ...
featureGates:
  InsightsOperatorPullingSCA: true,
  LegacyNodeRoleBehavior: false
# ...

    The features that are listed as true are enabled on your cluster.

    Note

    The features listed vary depending upon the OpenShift Container Platform version.

6.11.3. Enabling feature sets using the CLI

You can use the OpenShift CLI (oc) to enable feature sets for all of the nodes in a cluster by editing the FeatureGate custom resource (CR).

Prerequisites

  • You have installed the OpenShift CLI (oc).

Procedure

To enable feature sets:

  1. Edit the FeatureGate CR named cluster: 

    $ oc edit featuregate cluster
    Warning

    Enabling the TechPreviewNoUpgrade feature set on your cluster cannot be undone and prevents minor version updates. You should not enable this feature set on production clusters.

    Sample FeatureGate custom resource

    apiVersion: config.openshift.io/v1
kind: FeatureGate
metadata:
  name: cluster 1
# ...
spec:
  featureSet: TechPreviewNoUpgrade 2

    1
    The name of the FeatureGate CR must be cluster.
    2
    Add the feature set that you want to enable:
    • TechPreviewNoUpgrade enables specific Technology Preview features.

    After you save the changes, new machine configs are created, the machine config pools are updated, and scheduling on each node is disabled while the change is being applied.

Verification

You can verify that the feature gates are enabled by looking at the kubelet.conf file on a node after the nodes return to the ready state.

  1. From the Administrator perspective in the web console, navigate to Compute → Nodes.
  2. Select a node.
  3. In the Node details page, click Terminal.

  4. In the terminal window, change your root directory to /host: 

    sh-4.2# chroot /host

  5. View the kubelet.conf file: 

    sh-4.2# cat /etc/kubernetes/kubelet.conf

    Sample output

    # ...
featureGates:
  InsightsOperatorPullingSCA: true,
  LegacyNodeRoleBehavior: false
# ...

    The features that are listed as true are enabled on your cluster.

    Note

    The features listed vary depending upon the OpenShift Container Platform version.

6.12. etcd tasks

Back up etcd, enable or disable etcd encryption, or defragment etcd data.

6.12.1. About etcd encryption

By default, etcd data is not encrypted in OpenShift Container Platform. You can enable etcd encryption for your cluster to provide an additional layer of data security. For example, it can help protect the loss of sensitive data if an etcd backup is exposed to the incorrect parties.

When you enable etcd encryption, the following OpenShift API server and Kubernetes API server resources are encrypted:

  • Secrets
  • Config maps
  • Routes
  • OAuth access tokens
  • OAuth authorize tokens

When you enable etcd encryption, encryption keys are created. These keys are rotated on a weekly basis. You must have these keys to restore from an etcd backup.

Note

Etcd encryption only encrypts values, not keys. Resource types, namespaces, and object names are unencrypted.

If etcd encryption is enabled during a backup, the static_kuberesources_<datetimestamp>.tar.gz file contains the encryption keys for the etcd snapshot. For security reasons, store this file separately from the etcd snapshot. However, this file is required to restore a previous state of etcd from the respective etcd snapshot.

6.12.2. Enabling etcd encryption

You can enable etcd encryption to encrypt sensitive resources in your cluster.

Warning

Do not back up etcd resources until the initial encryption process is completed. If the encryption process is not completed, the backup might be only partially encrypted.

After you enable etcd encryption, several changes can occur:

  • The etcd encryption might affect the memory consumption of a few resources.
  • You might notice a transient affect on backup performance because the leader must serve the backup.
  • A disk I/O can affect the node that receives the backup state.

Prerequisites

  • Access to the cluster as a user with the cluster-admin role.

Procedure

  1. Modify the APIServer object: 

    $ oc edit apiserver

  2. Set the encryption field type to aescbc: 

    spec:
  encryption:
    type: aescbc 1
    1
    The aescbc type means that AES-CBC with PKCS#7 padding and a 32 byte key is used to perform the encryption.

  3. Save the file to apply the changes.

    The encryption process starts. It can take 20 minutes or longer for this process to complete, depending on the size of your cluster.

  4. Verify that etcd encryption was successful.

    1. Review the Encrypted status condition for the OpenShift API server to verify that its resources were successfully encrypted: 

      $ oc get openshiftapiserver -o=jsonpath='{range .items[0].status.conditions[?(@.type=="Encrypted")]}{.reason}{"\n"}{.message}{"\n"}'

      The output shows EncryptionCompleted upon successful encryption: 

      EncryptionCompleted
All resources encrypted: routes.route.openshift.io

      If the output shows EncryptionInProgress, encryption is still in progress. Wait a few minutes and try again.

    2. Review the Encrypted status condition for the Kubernetes API server to verify that its resources were successfully encrypted: 

      $ oc get kubeapiserver -o=jsonpath='{range .items[0].status.conditions[?(@.type=="Encrypted")]}{.reason}{"\n"}{.message}{"\n"}'

      The output shows EncryptionCompleted upon successful encryption: 

      EncryptionCompleted
All resources encrypted: secrets, configmaps

      If the output shows EncryptionInProgress, encryption is still in progress. Wait a few minutes and try again.

    3. Review the Encrypted status condition for the OpenShift OAuth API server to verify that its resources were successfully encrypted: 

      $ oc get authentication.operator.openshift.io -o=jsonpath='{range .items[0].status.conditions[?(@.type=="Encrypted")]}{.reason}{"\n"}{.message}{"\n"}'

      The output shows EncryptionCompleted upon successful encryption: 

      EncryptionCompleted
All resources encrypted: oauthaccesstokens.oauth.openshift.io, oauthauthorizetokens.oauth.openshift.io

      If the output shows EncryptionInProgress, encryption is still in progress. Wait a few minutes and try again.

6.12.3. Disabling etcd encryption

You can disable encryption of etcd data in your cluster.

Prerequisites

  • Access to the cluster as a user with the cluster-admin role.

Procedure

  1. Modify the APIServer object: 

    $ oc edit apiserver

  2. Set the encryption field type to identity: 

    spec:
  encryption:
    type: identity 1
    1
    The identity type is the default value and means that no encryption is performed.

  3. Save the file to apply the changes.

    The decryption process starts. It can take 20 minutes or longer for this process to complete, depending on the size of your cluster.

  4. Verify that etcd decryption was successful.

    1. Review the Encrypted status condition for the OpenShift API server to verify that its resources were successfully decrypted: 

      $ oc get openshiftapiserver -o=jsonpath='{range .items[0].status.conditions[?(@.type=="Encrypted")]}{.reason}{"\n"}{.message}{"\n"}'

      The output shows DecryptionCompleted upon successful decryption: 

      DecryptionCompleted
Encryption mode set to identity and everything is decrypted

      If the output shows DecryptionInProgress, decryption is still in progress. Wait a few minutes and try again.

    2. Review the Encrypted status condition for the Kubernetes API server to verify that its resources were successfully decrypted: 

      $ oc get kubeapiserver -o=jsonpath='{range .items[0].status.conditions[?(@.type=="Encrypted")]}{.reason}{"\n"}{.message}{"\n"}'

      The output shows DecryptionCompleted upon successful decryption: 

      DecryptionCompleted
Encryption mode set to identity and everything is decrypted

      If the output shows DecryptionInProgress, decryption is still in progress. Wait a few minutes and try again.

    3. Review the Encrypted status condition for the OpenShift OAuth API server to verify that its resources were successfully decrypted: 

      $ oc get authentication.operator.openshift.io -o=jsonpath='{range .items[0].status.conditions[?(@.type=="Encrypted")]}{.reason}{"\n"}{.message}{"\n"}'

      The output shows DecryptionCompleted upon successful decryption: 

      DecryptionCompleted
Encryption mode set to identity and everything is decrypted

      If the output shows DecryptionInProgress, decryption is still in progress. Wait a few minutes and try again.

6.12.4. Backing up etcd data

Follow these steps to back up etcd data by creating an etcd snapshot and backing up the resources for the static pods. This backup can be saved and used at a later time if you need to restore etcd.

Important

Only save a backup from a single control plane host. Do not take a backup from each control plane host in the cluster.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.

  • You have checked whether the cluster-wide proxy is enabled.

    Tip

    You can check whether the proxy is enabled by reviewing the output of oc get proxy cluster -o yaml. The proxy is enabled if the httpProxy, httpsProxy, and noProxy fields have values set.

Procedure

  1. Start a debug session as root for a control plane node: 

    $ oc debug --as-root node/<node_name>

  2. Change your root directory to /host in the debug shell: 

    sh-4.4# chroot /host

  3. If the cluster-wide proxy is enabled, export the NO_PROXY, HTTP_PROXY, and HTTPS_PROXY environment variables by running the following commands: 

    $ export HTTP_PROXY=http://<your_proxy.example.com>:8080
    $ export HTTPS_PROXY=https://<your_proxy.example.com>:8080
    $ export NO_PROXY=<example.com>

  4. Run the cluster-backup.sh script in the debug shell and pass in the location to save the backup to.

    Tip

    The cluster-backup.sh script is maintained as a component of the etcd Cluster Operator and is a wrapper around the etcdctl snapshot save command. 

    sh-4.4# /usr/local/bin/cluster-backup.sh /home/core/assets/backup

    Example script output

    found latest kube-apiserver: /etc/kubernetes/static-pod-resources/kube-apiserver-pod-6
found latest kube-controller-manager: /etc/kubernetes/static-pod-resources/kube-controller-manager-pod-7
found latest kube-scheduler: /etc/kubernetes/static-pod-resources/kube-scheduler-pod-6
found latest etcd: /etc/kubernetes/static-pod-resources/etcd-pod-3
ede95fe6b88b87ba86a03c15e669fb4aa5bf0991c180d3c6895ce72eaade54a1
etcdctl version: 3.4.14
API version: 3.4
{"level":"info","ts":1624647639.0188997,"caller":"snapshot/v3_snapshot.go:119","msg":"created temporary db file","path":"/home/core/assets/backup/snapshot_2021-06-25_190035.db.part"}
{"level":"info","ts":"2021-06-25T19:00:39.030Z","caller":"clientv3/maintenance.go:200","msg":"opened snapshot stream; downloading"}
{"level":"info","ts":1624647639.0301006,"caller":"snapshot/v3_snapshot.go:127","msg":"fetching snapshot","endpoint":"https://10.0.0.5:2379"}
{"level":"info","ts":"2021-06-25T19:00:40.215Z","caller":"clientv3/maintenance.go:208","msg":"completed snapshot read; closing"}
{"level":"info","ts":1624647640.6032252,"caller":"snapshot/v3_snapshot.go:142","msg":"fetched snapshot","endpoint":"https://10.0.0.5:2379","size":"114 MB","took":1.584090459}
{"level":"info","ts":1624647640.6047094,"caller":"snapshot/v3_snapshot.go:152","msg":"saved","path":"/home/core/assets/backup/snapshot_2021-06-25_190035.db"}
Snapshot saved at /home/core/assets/backup/snapshot_2021-06-25_190035.db
{"hash":3866667823,"revision":31407,"totalKey":12828,"totalSize":114446336}
snapshot db and kube resources are successfully saved to /home/core/assets/backup

    In this example, two files are created in the /home/core/assets/backup/ directory on the control plane host:

    • snapshot_<datetimestamp>.db: This file is the etcd snapshot. The cluster-backup.sh script confirms its validity.

    • static_kuberesources_<datetimestamp>.tar.gz: This file contains the resources for the static pods. If etcd encryption is enabled, it also contains the encryption keys for the etcd snapshot.

      Note

      If etcd encryption is enabled, it is recommended to store this second file separately from the etcd snapshot for security reasons. However, this file is required to restore from the etcd snapshot.

      Keep in mind that etcd encryption only encrypts values, not keys. This means that resource types, namespaces, and object names are unencrypted.

6.12.5. Defragmenting etcd data

For large and dense clusters, etcd can suffer from poor performance if the keyspace grows too large and exceeds the space quota. Periodically maintain and defragment etcd to free up space in the data store. Monitor Prometheus for etcd metrics and defragment it when required; otherwise, etcd can raise a cluster-wide alarm that puts the cluster into a maintenance mode that accepts only key reads and deletes.

Monitor these key metrics:

  • etcd_server_quota_backend_bytes, which is the current quota limit
  • etcd_mvcc_db_total_size_in_use_in_bytes, which indicates the actual database usage after a history compaction
  • etcd_mvcc_db_total_size_in_bytes, which shows the database size, including free space waiting for defragmentation

Defragment etcd data to reclaim disk space after events that cause disk fragmentation, such as etcd history compaction.

History compaction is performed automatically every five minutes and leaves gaps in the back-end database. This fragmented space is available for use by etcd, but is not available to the host file system. You must defragment etcd to make this space available to the host file system.

Defragmentation occurs automatically, but you can also trigger it manually.

Note

Automatic defragmentation is good for most cases, because the etcd operator uses cluster information to determine the most efficient operation for the user.

6.12.5.1. Automatic defragmentation

The etcd Operator automatically defragments disks. No manual intervention is needed.

Verify that the defragmentation process is successful by viewing one of these logs:

  • etcd logs
  • cluster-etcd-operator pod
  • operator status error log
Warning

Automatic defragmentation can cause leader election failure in various OpenShift core components, such as the Kubernetes controller manager, which triggers a restart of the failing component. The restart is harmless and either triggers failover to the next running instance or the component resumes work again after the restart.

Example log output for successful defragmentation

etcd member has been defragmented: <member_name>, memberID: <member_id>

Example log output for unsuccessful defragmentation

failed defrag on member: <member_name>, memberID: <member_id>: <error_message>

6.12.5.2. Manual defragmentation

A Prometheus alert indicates when you need to use manual defragmentation. The alert is displayed in two cases:

  • When etcd uses more than 50% of its available space for more than 10 minutes
  • When etcd is actively using less than 50% of its total database size for more than 10 minutes

You can also determine whether defragmentation is needed by checking the etcd database size in MB that will be freed by defragmentation with the PromQL expression: (etcd_mvcc_db_total_size_in_bytes - etcd_mvcc_db_total_size_in_use_in_bytes)/1024/1024

Warning

Defragmenting etcd is a blocking action. The etcd member will not respond until defragmentation is complete. For this reason, wait at least one minute between defragmentation actions on each of the pods to allow the cluster to recover.

Follow this procedure to defragment etcd data on each etcd member.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.

Procedure

  1. Determine which etcd member is the leader, because the leader should be defragmented last.

    1. Get the list of etcd pods: 

      $ oc -n openshift-etcd get pods -l k8s-app=etcd -o wide

      Example output

      etcd-ip-10-0-159-225.example.redhat.com                3/3     Running     0          175m   10.0.159.225   ip-10-0-159-225.example.redhat.com   <none>           <none>
etcd-ip-10-0-191-37.example.redhat.com                 3/3     Running     0          173m   10.0.191.37    ip-10-0-191-37.example.redhat.com    <none>           <none>
etcd-ip-10-0-199-170.example.redhat.com                3/3     Running     0          176m   10.0.199.170   ip-10-0-199-170.example.redhat.com   <none>           <none>

    2. Choose a pod and run the following command to determine which etcd member is the leader: 

      $ oc rsh -n openshift-etcd etcd-ip-10-0-159-225.example.redhat.com etcdctl endpoint status --cluster -w table

      Example output

      Defaulting container name to etcdctl.
Use 'oc describe pod/etcd-ip-10-0-159-225.example.redhat.com -n openshift-etcd' to see all of the containers in this pod.
+---------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|         ENDPOINT          |        ID        | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |
+---------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|  https://10.0.191.37:2379 | 251cd44483d811c3 |   3.4.9 |  104 MB |     false |      false |         7 |      91624 |              91624 |        |
| https://10.0.159.225:2379 | 264c7c58ecbdabee |   3.4.9 |  104 MB |     false |      false |         7 |      91624 |              91624 |        |
| https://10.0.199.170:2379 | 9ac311f93915cc79 |   3.4.9 |  104 MB |      true |      false |         7 |      91624 |              91624 |        |
+---------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+

      Based on the IS LEADER column of this output, the https://10.0.199.170:2379 endpoint is the leader. Matching this endpoint with the output of the previous step, the pod name of the leader is etcd-ip-10-0-199-170.example.redhat.com.

  2. Defragment an etcd member.

    1. Connect to the running etcd container, passing in the name of a pod that is not the leader: 

      $ oc rsh -n openshift-etcd etcd-ip-10-0-159-225.example.redhat.com

    2. Unset the ETCDCTL_ENDPOINTS environment variable: 

      sh-4.4# unset ETCDCTL_ENDPOINTS

    3. Defragment the etcd member: 

      sh-4.4# etcdctl --command-timeout=30s --endpoints=https://localhost:2379 defrag

      Example output

      Finished defragmenting etcd member[https://localhost:2379]

      If a timeout error occurs, increase the value for --command-timeout until the command succeeds.

    4. Verify that the database size was reduced: 

      sh-4.4# etcdctl endpoint status -w table --cluster

      Example output

      +---------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|         ENDPOINT          |        ID        | VERSION | DB SIZE | IS LEADER | IS LEARNER | RAFT TERM | RAFT INDEX | RAFT APPLIED INDEX | ERRORS |
+---------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+
|  https://10.0.191.37:2379 | 251cd44483d811c3 |   3.4.9 |  104 MB |     false |      false |         7 |      91624 |              91624 |        |
| https://10.0.159.225:2379 | 264c7c58ecbdabee |   3.4.9 |   41 MB |     false |      false |         7 |      91624 |              91624 |        | 1
| https://10.0.199.170:2379 | 9ac311f93915cc79 |   3.4.9 |  104 MB |      true |      false |         7 |      91624 |              91624 |        |
+---------------------------+------------------+---------+---------+-----------+------------+-----------+------------+--------------------+--------+

      This example shows that the database size for this etcd member is now 41 MB as opposed to the starting size of 104 MB.

    5. Repeat these steps to connect to each of the other etcd members and defragment them. Always defragment the leader last.

      Wait at least one minute between defragmentation actions to allow the etcd pod to recover. Until the etcd pod recovers, the etcd member will not respond.

  3. If any NOSPACE alarms were triggered due to the space quota being exceeded, clear them.

    1. Check if there are any NOSPACE alarms: 

      sh-4.4# etcdctl alarm list

      Example output

      memberID:12345678912345678912 alarm:NOSPACE

    2. Clear the alarms: 

      sh-4.4# etcdctl alarm disarm

6.12.6. Restoring to a previous cluster state

You can use a saved etcd backup to restore a previous cluster state or restore a cluster that has lost the majority of control plane hosts.

Note

If your cluster uses a control plane machine set, see "Troubleshooting the control plane machine set" for a more simple etcd recovery procedure.

Important

When you restore your cluster, you must use an etcd backup that was taken from the same z-stream release. For example, an OpenShift Container Platform 4.7.2 cluster must use an etcd backup that was taken from 4.7.2.

Prerequisites

  • Access to the cluster as a user with the cluster-admin role through a certificate-based kubeconfig file, like the one that was used during installation.
  • A healthy control plane host to use as the recovery host.
  • SSH access to control plane hosts.
  • A backup directory containing both the etcd snapshot and the resources for the static pods, which were from the same backup. The file names in the directory must be in the following formats: snapshot_<datetimestamp>.db and static_kuberesources_<datetimestamp>.tar.gz.
Important

For non-recovery control plane nodes, it is not required to establish SSH connectivity or to stop the static pods. You can delete and recreate other non-recovery, control plane machines, one by one.

Procedure

  1. Select a control plane host to use as the recovery host. This is the host that you will run the restore operation on.

  2. Establish SSH connectivity to each of the control plane nodes, including the recovery host.

    The Kubernetes API server becomes inaccessible after the restore process starts, so you cannot access the control plane nodes. For this reason, it is recommended to establish SSH connectivity to each control plane host in a separate terminal.

    Important

    If you do not complete this step, you will not be able to access the control plane hosts to complete the restore procedure, and you will be unable to recover your cluster from this state.

  3. Copy the etcd backup directory to the recovery control plane host.

    This procedure assumes that you copied the backup directory containing the etcd snapshot and the resources for the static pods to the /home/core/ directory of your recovery control plane host.

  4. Stop the static pods on any other control plane nodes.

    Note

    You do not need to stop the static pods on the recovery host.

    1. Access a control plane host that is not the recovery host.

    2. Move the existing etcd pod file out of the kubelet manifest directory: 

      $ sudo mv -v /etc/kubernetes/manifests/etcd-pod.yaml /tmp

    3. Verify that the etcd pods are stopped. 

      $ sudo crictl ps | grep etcd | egrep -v "operator|etcd-guard"

      The output of this command should be empty. If it is not empty, wait a few minutes and check again.

    4. Move the existing Kubernetes API server pod file out of the kubelet manifest directory: 

      $ sudo mv -v /etc/kubernetes/manifests/kube-apiserver-pod.yaml /tmp

    5. Verify that the Kubernetes API server pods are stopped. 

      $ sudo crictl ps | grep kube-apiserver | egrep -v "operator|guard"

      The output of this command should be empty. If it is not empty, wait a few minutes and check again.

    6. Move the etcd data directory to a different location: 

      $ sudo mv -v /var/lib/etcd/ /tmp

    7. If the /etc/kubernetes/manifests/keepalived.yaml file exists and the node is deleted, follow these steps:

      1. Move the /etc/kubernetes/manifests/keepalived.yaml file out of the kubelet manifest directory: 

        $ sudo mv -v /etc/kubernetes/manifests/keepalived.yaml /tmp

      2. Verify that any containers managed by the keepalived daemon are stopped: 

        $ sudo crictl ps --name keepalived

        The output of this command should be empty. If it is not empty, wait a few minutes and check again.

      3. Check if the control plane has any Virtual IPs (VIPs) assigned to it: 

        $ ip -o address | egrep '<api_vip>|<ingress_vip>'

      4. For each reported VIP, run the following command to remove it: 

        $ sudo ip address del <reported_vip> dev <reported_vip_device>
    8. Repeat this step on each of the other control plane hosts that is not the recovery host.
  5. Access the recovery control plane host.

  6. If the keepalived daemon is in use, verify that the recovery control plane node owns the VIP: 

    $ ip -o address | grep <api_vip>

    The address of the VIP is highlighted in the output if it exists. This command returns an empty string if the VIP is not set or configured incorrectly.

  7. If the cluster-wide proxy is enabled, be sure that you have exported the NO_PROXY, HTTP_PROXY, and HTTPS_PROXY environment variables.

    Tip

    You can check whether the proxy is enabled by reviewing the output of oc get proxy cluster -o yaml. The proxy is enabled if the httpProxy, httpsProxy, and noProxy fields have values set.

  8. Run the restore script on the recovery control plane host and pass in the path to the etcd backup directory: 

    $ sudo -E /usr/local/bin/cluster-restore.sh /home/core/assets/backup

    Example script output

    ...stopping kube-scheduler-pod.yaml
...stopping kube-controller-manager-pod.yaml
...stopping etcd-pod.yaml
...stopping kube-apiserver-pod.yaml
Waiting for container etcd to stop
.complete
Waiting for container etcdctl to stop
.............................complete
Waiting for container etcd-metrics to stop
complete
Waiting for container kube-controller-manager to stop
complete
Waiting for container kube-apiserver to stop
..........................................................................................complete
Waiting for container kube-scheduler to stop
complete
Moving etcd data-dir /var/lib/etcd/member to /var/lib/etcd-backup
starting restore-etcd static pod
starting kube-apiserver-pod.yaml
static-pod-resources/kube-apiserver-pod-7/kube-apiserver-pod.yaml
starting kube-controller-manager-pod.yaml
static-pod-resources/kube-controller-manager-pod-7/kube-controller-manager-pod.yaml
starting kube-scheduler-pod.yaml
static-pod-resources/kube-scheduler-pod-8/kube-scheduler-pod.yaml

    Note

    The restore process can cause nodes to enter the NotReady state if the node certificates were updated after the last etcd backup.

  9. Check the nodes to ensure they are in the Ready state.

    1. Run the following command: 

      $ oc get nodes -w

      Sample output

      NAME                STATUS  ROLES          AGE     VERSION
host-172-25-75-28   Ready   master         3d20h   v1.25.0
host-172-25-75-38   Ready   infra,worker   3d20h   v1.25.0
host-172-25-75-40   Ready   master         3d20h   v1.25.0
host-172-25-75-65   Ready   master         3d20h   v1.25.0
host-172-25-75-74   Ready   infra,worker   3d20h   v1.25.0
host-172-25-75-79   Ready   worker         3d20h   v1.25.0
host-172-25-75-86   Ready   worker         3d20h   v1.25.0
host-172-25-75-98   Ready   infra,worker   3d20h   v1.25.0

      It can take several minutes for all nodes to report their state.

    2. If any nodes are in the NotReady state, log in to the nodes and remove all of the PEM files from the /var/lib/kubelet/pki directory on each node. You can SSH into the nodes or use the terminal window in the web console. 

      $  ssh -i <ssh-key-path> core@<master-hostname>

      Sample pki directory

      sh-4.4# pwd
/var/lib/kubelet/pki
sh-4.4# ls
kubelet-client-2022-04-28-11-24-09.pem  kubelet-server-2022-04-28-11-24-15.pem
kubelet-client-current.pem              kubelet-server-current.pem

  10. Restart the kubelet service on all control plane hosts.

    1. From the recovery host, run the following command: 

      $ sudo systemctl restart kubelet.service
    2. Repeat this step on all other control plane hosts.

  11. Approve the pending CSRs:

    Note

    Clusters with no worker nodes, such as single-node clusters or clusters consisting of three schedulable control plane nodes, will not have any pending CSRs to approve. You can skip all the commands listed in this step.

    1. Get the list of current CSRs: 

      $ oc get csr

      Example output

      NAME        AGE    SIGNERNAME                                    REQUESTOR                                                                   CONDITION
csr-2s94x   8m3s   kubernetes.io/kubelet-serving                 system:node:<node_name>                                                     Pending 1
csr-4bd6t   8m3s   kubernetes.io/kubelet-serving                 system:node:<node_name>                                                     Pending 2
csr-4hl85   13m    kubernetes.io/kube-apiserver-client-kubelet   system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending 3
csr-zhhhp   3m8s   kubernetes.io/kube-apiserver-client-kubelet   system:serviceaccount:openshift-machine-config-operator:node-bootstrapper   Pending 4
...

      1 1 2
      A pending kubelet service CSR (for user-provisioned installations).
      3 4
      A pending node-bootstrapper CSR.

    2. Review the details of a CSR to verify that it is valid: 

      $ oc describe csr <csr_name> 1
      1
      <csr_name> is the name of a CSR from the list of current CSRs.

    3. Approve each valid node-bootstrapper CSR: 

      $ oc adm certificate approve <csr_name>

    4. For user-provisioned installations, approve each valid kubelet service CSR: 

      $ oc adm certificate approve <csr_name>

  12. Verify that the single member control plane has started successfully.

    1. From the recovery host, verify that the etcd container is running. 

      $ sudo crictl ps | grep etcd | egrep -v "operator|etcd-guard"

      Example output

      3ad41b7908e32       36f86e2eeaaffe662df0d21041eb22b8198e0e58abeeae8c743c3e6e977e8009                                                         About a minute ago   Running             etcd                                          0                   7c05f8af362f0

    2. From the recovery host, verify that the etcd pod is running. 

      $ oc -n openshift-etcd get pods -l k8s-app=etcd

      Example output

      NAME                                             READY   STATUS      RESTARTS   AGE
etcd-ip-10-0-143-125.ec2.internal                1/1     Running     1          2m47s

      If the status is Pending, or the output lists more than one running etcd pod, wait a few minutes and check again.

  13. If you are using the OVNKubernetes network plugin, delete the node objects that are associated with control plane hosts that are not the recovery control plane host. 

    $ oc delete node <non-recovery-controlplane-host-1> <non-recovery-controlplane-host-2>

  14. Verify that the Cluster Network Operator (CNO) redeploys the OVN-Kubernetes control plane and that it no longer references the non-recovery controller IP addresses. To verify this result, regularly check the output of the following command. Wait until it returns an empty result before you proceed to restart the Open Virtual Network (OVN) Kubernetes pods on all of the hosts in the next step. 

    $ oc -n openshift-ovn-kubernetes get ds/ovnkube-master -o yaml | grep -E '<non-recovery_controller_ip_1>|<non-recovery_controller_ip_2>'
    Note

    It can take at least 5-10 minutes for the OVN-Kubernetes control plane to be redeployed and the previous command to return empty output.

  15. If you are using the OVN-Kubernetes network plugin, restart the Open Virtual Network (OVN) Kubernetes pods on all of the hosts.

    Note

    Validating and mutating admission webhooks can reject pods. If you add any additional webhooks with the failurePolicy set to Fail, then they can reject pods and the restoration process can fail. You can avoid this by saving and deleting webhooks while restoring the cluster state. After the cluster state is restored successfully, you can enable the webhooks again.

    Alternatively, you can temporarily set the failurePolicy to Ignore while restoring the cluster state. After the cluster state is restored successfully, you can set the failurePolicy to Fail.

    1. Remove the northbound database (nbdb) and southbound database (sbdb). Access the recovery host and the remaining control plane nodes by using Secure Shell (SSH) and run the following command: 

      $ sudo rm -f /var/lib/ovn/etc/*.db

    2. Delete all OVN-Kubernetes control plane pods by running the following command: 

      $ oc delete pods -l app=ovnkube-master -n openshift-ovn-kubernetes

    3. Ensure that any OVN-Kubernetes control plane pods are deployed again and are in a Running state by running the following command: 

      $ oc get pods -l app=ovnkube-master -n openshift-ovn-kubernetes

      Example output

      NAME                   READY   STATUS    RESTARTS   AGE
ovnkube-master-nb24h   4/4     Running   0          48s

    4. Delete all ovnkube-node pods by running the following command: 

      $ oc get pods -n openshift-ovn-kubernetes -o name | grep ovnkube-node | while read p ; do oc delete $p -n openshift-ovn-kubernetes ; done

    5. Ensure that all the ovnkube-node pods are deployed again and are in a Running state by running the following command: 

      $ oc get  pods -n openshift-ovn-kubernetes | grep ovnkube-node

  16. Delete and re-create other non-recovery, control plane machines, one by one. After the machines are re-created, a new revision is forced and etcd automatically scales up.

    • If you use a user-provisioned bare metal installation, you can re-create a control plane machine by using the same method that you used to originally create it. For more information, see "Installing a user-provisioned cluster on bare metal".

      Warning

      Do not delete and re-create the machine for the recovery host.

    • If you are running installer-provisioned infrastructure, or you used the Machine API to create your machines, follow these steps:

      Warning

      Do not delete and re-create the machine for the recovery host.

      For bare metal installations on installer-provisioned infrastructure, control plane machines are not re-created. For more information, see "Replacing a bare-metal control plane node".

      1. Obtain the machine for one of the lost control plane hosts.

        In a terminal that has access to the cluster as a cluster-admin user, run the following command: 

        $ oc get machines -n openshift-machine-api -o wide

        Example output: 

        NAME                                        PHASE     TYPE        REGION      ZONE         AGE     NODE                           PROVIDERID                              STATE
clustername-8qw5l-master-0                  Running   m4.xlarge   us-east-1   us-east-1a   3h37m   ip-10-0-131-183.ec2.internal   aws:///us-east-1a/i-0ec2782f8287dfb7e   stopped 1
clustername-8qw5l-master-1                  Running   m4.xlarge   us-east-1   us-east-1b   3h37m   ip-10-0-143-125.ec2.internal   aws:///us-east-1b/i-096c349b700a19631   running
clustername-8qw5l-master-2                  Running   m4.xlarge   us-east-1   us-east-1c   3h37m   ip-10-0-154-194.ec2.internal    aws:///us-east-1c/i-02626f1dba9ed5bba  running
clustername-8qw5l-worker-us-east-1a-wbtgd   Running   m4.large    us-east-1   us-east-1a   3h28m   ip-10-0-129-226.ec2.internal   aws:///us-east-1a/i-010ef6279b4662ced   running
clustername-8qw5l-worker-us-east-1b-lrdxb   Running   m4.large    us-east-1   us-east-1b   3h28m   ip-10-0-144-248.ec2.internal   aws:///us-east-1b/i-0cb45ac45a166173b   running
clustername-8qw5l-worker-us-east-1c-pkg26   Running   m4.large    us-east-1   us-east-1c   3h28m   ip-10-0-170-181.ec2.internal   aws:///us-east-1c/i-06861c00007751b0a   running
        1
        This is the control plane machine for the lost control plane host, ip-10-0-131-183.ec2.internal.

      2. Delete the machine of the lost control plane host by running: 

        $ oc delete machine -n openshift-machine-api clustername-8qw5l-master-0 1
        1
        Specify the name of the control plane machine for the lost control plane host.

        A new machine is automatically provisioned after deleting the machine of the lost control plane host.

      3. Verify that a new machine has been created by running: 

        $ oc get machines -n openshift-machine-api -o wide

        Example output: 

        NAME                                        PHASE          TYPE        REGION      ZONE         AGE     NODE                           PROVIDERID                              STATE
clustername-8qw5l-master-1                  Running        m4.xlarge   us-east-1   us-east-1b   3h37m   ip-10-0-143-125.ec2.internal   aws:///us-east-1b/i-096c349b700a19631   running
clustername-8qw5l-master-2                  Running        m4.xlarge   us-east-1   us-east-1c   3h37m   ip-10-0-154-194.ec2.internal    aws:///us-east-1c/i-02626f1dba9ed5bba  running
clustername-8qw5l-master-3                  Provisioning   m4.xlarge   us-east-1   us-east-1a   85s     ip-10-0-173-171.ec2.internal    aws:///us-east-1a/i-015b0888fe17bc2c8  running 1
clustername-8qw5l-worker-us-east-1a-wbtgd   Running        m4.large    us-east-1   us-east-1a   3h28m   ip-10-0-129-226.ec2.internal   aws:///us-east-1a/i-010ef6279b4662ced   running
clustername-8qw5l-worker-us-east-1b-lrdxb   Running        m4.large    us-east-1   us-east-1b   3h28m   ip-10-0-144-248.ec2.internal   aws:///us-east-1b/i-0cb45ac45a166173b   running
clustername-8qw5l-worker-us-east-1c-pkg26   Running        m4.large    us-east-1   us-east-1c   3h28m   ip-10-0-170-181.ec2.internal   aws:///us-east-1c/i-06861c00007751b0a   running
        1
        The new machine, clustername-8qw5l-master-3 is being created and is ready after the phase changes from Provisioning to Running.

        It might take a few minutes for the new machine to be created. The etcd cluster Operator will automatically sync when the machine or node returns to a healthy state.

      4. Repeat these steps for each lost control plane host that is not the recovery host.

  17. Turn off the quorum guard by entering the following command: 

    $ oc patch etcd/cluster --type=merge -p '{"spec": {"unsupportedConfigOverrides": {"useUnsupportedUnsafeNonHANonProductionUnstableEtcd": true}}}'

    This command ensures that you can successfully re-create secrets and roll out the static pods.

  18. In a separate terminal window within the recovery host, export the recovery kubeconfig file by running the following command: 

    $ export KUBECONFIG=/etc/kubernetes/static-pod-resources/kube-apiserver-certs/secrets/node-kubeconfigs/localhost-recovery.kubeconfig

  19. Force etcd redeployment.

    In the same terminal window where you exported the recovery kubeconfig file, run the following command: 

    $ oc patch etcd cluster -p='{"spec": {"forceRedeploymentReason": "recovery-'"$( date --rfc-3339=ns )"'"}}' --type=merge 1
    1
    The forceRedeploymentReason value must be unique, which is why a timestamp is appended.

    When the etcd cluster Operator performs a redeployment, the existing nodes are started with new pods similar to the initial bootstrap scale up.

  20. Turn the quorum guard back on by entering the following command: 

    $ oc patch etcd/cluster --type=merge -p '{"spec": {"unsupportedConfigOverrides": null}}'

  21. You can verify that the unsupportedConfigOverrides section is removed from the object by entering this command: 

    $ oc get etcd/cluster -oyaml

  22. Verify all nodes are updated to the latest revision.

    In a terminal that has access to the cluster as a cluster-admin user, run the following command: 

    $ oc get etcd -o=jsonpath='{range .items[0].status.conditions[?(@.type=="NodeInstallerProgressing")]}{.reason}{"\n"}{.message}{"\n"}'

    Review the NodeInstallerProgressing status condition for etcd to verify that all nodes are at the latest revision. The output shows AllNodesAtLatestRevision upon successful update: 

    AllNodesAtLatestRevision
3 nodes are at revision 7 1
    1
    In this example, the latest revision number is 7.

    If the output includes multiple revision numbers, such as 2 nodes are at revision 6; 1 nodes are at revision 7, this means that the update is still in progress. Wait a few minutes and try again.

  23. After etcd is redeployed, force new rollouts for the control plane. The Kubernetes API server will reinstall itself on the other nodes because the kubelet is connected to API servers using an internal load balancer.

    In a terminal that has access to the cluster as a cluster-admin user, run the following commands.

    1. Force a new rollout for the Kubernetes API server: 

      $ oc patch kubeapiserver cluster -p='{"spec": {"forceRedeploymentReason": "recovery-'"$( date --rfc-3339=ns )"'"}}' --type=merge

      Verify all nodes are updated to the latest revision. 

      $ oc get kubeapiserver -o=jsonpath='{range .items[0].status.conditions[?(@.type=="NodeInstallerProgressing")]}{.reason}{"\n"}{.message}{"\n"}'

      Review the NodeInstallerProgressing status condition to verify that all nodes are at the latest revision. The output shows AllNodesAtLatestRevision upon successful update: 

      AllNodesAtLatestRevision
3 nodes are at revision 7 1
      1
      In this example, the latest revision number is 7.

      If the output includes multiple revision numbers, such as 2 nodes are at revision 6; 1 nodes are at revision 7, this means that the update is still in progress. Wait a few minutes and try again.

    2. Force a new rollout for the Kubernetes controller manager: 

      $ oc patch kubecontrollermanager cluster -p='{"spec": {"forceRedeploymentReason": "recovery-'"$( date --rfc-3339=ns )"'"}}' --type=merge

      Verify all nodes are updated to the latest revision. 

      $ oc get kubecontrollermanager -o=jsonpath='{range .items[0].status.conditions[?(@.type=="NodeInstallerProgressing")]}{.reason}{"\n"}{.message}{"\n"}'

      Review the NodeInstallerProgressing status condition to verify that all nodes are at the latest revision. The output shows AllNodesAtLatestRevision upon successful update: 

      AllNodesAtLatestRevision
3 nodes are at revision 7 1
      1
      In this example, the latest revision number is 7.

      If the output includes multiple revision numbers, such as 2 nodes are at revision 6; 1 nodes are at revision 7, this means that the update is still in progress. Wait a few minutes and try again.

    3. Force a new rollout for the Kubernetes scheduler: 

      $ oc patch kubescheduler cluster -p='{"spec": {"forceRedeploymentReason": "recovery-'"$( date --rfc-3339=ns )"'"}}' --type=merge

      Verify all nodes are updated to the latest revision. 

      $ oc get kubescheduler -o=jsonpath='{range .items[0].status.conditions[?(@.type=="NodeInstallerProgressing")]}{.reason}{"\n"}{.message}{"\n"}'

      Review the NodeInstallerProgressing status condition to verify that all nodes are at the latest revision. The output shows AllNodesAtLatestRevision upon successful update: 

      AllNodesAtLatestRevision
3 nodes are at revision 7 1
      1
      In this example, the latest revision number is 7.

      If the output includes multiple revision numbers, such as 2 nodes are at revision 6; 1 nodes are at revision 7, this means that the update is still in progress. Wait a few minutes and try again.

  24. Verify that all control plane hosts have started and joined the cluster.

    In a terminal that has access to the cluster as a cluster-admin user, run the following command: 

    $ oc -n openshift-etcd get pods -l k8s-app=etcd

    Example output

    etcd-ip-10-0-143-125.ec2.internal                2/2     Running     0          9h
etcd-ip-10-0-154-194.ec2.internal                2/2     Running     0          9h
etcd-ip-10-0-173-171.ec2.internal                2/2     Running     0          9h

To ensure that all workloads return to normal operation following a recovery procedure, restart each pod that stores Kubernetes API information. This includes OpenShift Container Platform components such as routers, Operators, and third-party components.

Note

On completion of the previous procedural steps, you might need to wait a few minutes for all services to return to their restored state. For example, authentication by using oc login might not immediately work until the OAuth server pods are restarted.

Consider using the system:admin kubeconfig file for immediate authentication. This method basis its authentication on SSL/TLS client certificates as against OAuth tokens. You can authenticate with this file by issuing the following command: 

$ export KUBECONFIG=<installation_directory>/auth/kubeconfig

Issue the following command to display your authenticated user name: 

$ oc whoami

Additional resources

6.12.7. Issues and workarounds for restoring a persistent storage state

If your OpenShift Container Platform cluster uses persistent storage of any form, a state of the cluster is typically stored outside etcd. It might be an Elasticsearch cluster running in a pod or a database running in a StatefulSet object. When you restore from an etcd backup, the status of the workloads in OpenShift Container Platform is also restored. However, if the etcd snapshot is old, the status might be invalid or outdated.

Important

The contents of persistent volumes (PVs) are never part of the etcd snapshot. When you restore an OpenShift Container Platform cluster from an etcd snapshot, non-critical workloads might gain access to critical data, or vice-versa.

The following are some example scenarios that produce an out-of-date status:

  • MySQL database is running in a pod backed up by a PV object. Restoring OpenShift Container Platform from an etcd snapshot does not bring back the volume on the storage provider, and does not produce a running MySQL pod, despite the pod repeatedly attempting to start. You must manually restore this pod by restoring the volume on the storage provider, and then editing the PV to point to the new volume.
  • Pod P1 is using volume A, which is attached to node X. If the etcd snapshot is taken while another pod uses the same volume on node Y, then when the etcd restore is performed, pod P1 might not be able to start correctly due to the volume still being attached to node Y. OpenShift Container Platform is not aware of the attachment, and does not automatically detach it. When this occurs, the volume must be manually detached from node Y so that the volume can attach on node X, and then pod P1 can start.
  • Cloud provider or storage provider credentials were updated after the etcd snapshot was taken. This causes any CSI drivers or Operators that depend on the those credentials to not work. You might have to manually update the credentials required by those drivers or Operators.

  • A device is removed or renamed from OpenShift Container Platform nodes after the etcd snapshot is taken. The Local Storage Operator creates symlinks for each PV that it manages from /dev/disk/by-id or /dev directories. This situation might cause the local PVs to refer to devices that no longer exist.

    To fix this problem, an administrator must:

    1. Manually remove the PVs with invalid devices.
    2. Remove symlinks from respective nodes.
    3. Delete LocalVolume or LocalVolumeSet objects (see Storage → Configuring persistent storage → Persistent storage using local volumes → Deleting the Local Storage Operator Resources).

6.13. Pod disruption budgets

Understand and configure pod disruption budgets.

6.13.1. Understanding how to use pod disruption budgets to specify the number of pods that must be up

A pod disruption budget allows the specification of safety constraints on pods during operations, such as draining a node for maintenance.

PodDisruptionBudget is an API object that specifies the minimum number or percentage of replicas that must be up at a time. Setting these in projects can be helpful during node maintenance (such as scaling a cluster down or a cluster upgrade) and is only honored on voluntary evictions (not on node failures).

A PodDisruptionBudget object’s configuration consists of the following key parts:

  • A label selector, which is a label query over a set of pods.

  • An availability level, which specifies the minimum number of pods that must be available simultaneously, either:

    • minAvailable is the number of pods must always be available, even during a disruption.
    • maxUnavailable is the number of pods can be unavailable during a disruption.
Note

Available refers to the number of pods that has condition Ready=True. Ready=True refers to the pod that is able to serve requests and should be added to the load balancing pools of all matching services.

A maxUnavailable of 0% or 0 or a minAvailable of 100% or equal to the number of replicas is permitted but can block nodes from being drained.

You can check for pod disruption budgets across all projects with the following: 

$ oc get poddisruptionbudget --all-namespaces

Example output

NAMESPACE                              NAME                                    MIN AVAILABLE   MAX UNAVAILABLE   ALLOWED DISRUPTIONS   AGE
openshift-apiserver                    openshift-apiserver-pdb                 N/A             1                 1                     121m
openshift-cloud-controller-manager     aws-cloud-controller-manager            1               N/A               1                     125m
openshift-cloud-credential-operator    pod-identity-webhook                    1               N/A               1                     117m
openshift-cluster-csi-drivers          aws-ebs-csi-driver-controller-pdb       N/A             1                 1                     121m
openshift-cluster-storage-operator     csi-snapshot-controller-pdb             N/A             1                 1                     122m
openshift-cluster-storage-operator     csi-snapshot-webhook-pdb                N/A             1                 1                     122m
openshift-console                      console                                 N/A             1                 1                     116m
#...

The PodDisruptionBudget is considered healthy when there are at least minAvailable pods running in the system. Every pod above that limit can be evicted.

Note

Depending on your pod priority and preemption settings, lower-priority pods might be removed despite their pod disruption budget requirements.

6.13.2. Specifying the number of pods that must be up with pod disruption budgets

You can use a PodDisruptionBudget object to specify the minimum number or percentage of replicas that must be up at a time.

Procedure

To configure a pod disruption budget:

  1. Create a YAML file with the an object definition similar to the following: 

    apiVersion: policy/v1 1
kind: PodDisruptionBudget
metadata:
  name: my-pdb
spec:
  minAvailable: 2  2
  selector:  3
    matchLabels:
      name: my-pod
    1
    PodDisruptionBudget is part of the policy/v1 API group.
    2
    The minimum number of pods that must be available simultaneously. This can be either an integer or a string specifying a percentage, for example, 20%.
    3
    A label query over a set of resources. The result of matchLabels and matchExpressions are logically conjoined. Leave this paramter blank, for example selector {}, to select all pods in the project.

    Or: 

    apiVersion: policy/v1 1
kind: PodDisruptionBudget
metadata:
  name: my-pdb
spec:
  maxUnavailable: 25% 2
  selector: 3
    matchLabels:
      name: my-pod
    1
    PodDisruptionBudget is part of the policy/v1 API group.
    2
    The maximum number of pods that can be unavailable simultaneously. This can be either an integer or a string specifying a percentage, for example, 20%.
    3
    A label query over a set of resources. The result of matchLabels and matchExpressions are logically conjoined. Leave this paramter blank, for example selector {}, to select all pods in the project.

  2. Run the following command to add the object to project: 

    $ oc create -f </path/to/file> -n <project_name>

6.14. Rotating or removing cloud provider credentials

After installing OpenShift Container Platform, some organizations require the rotation or removal of the cloud provider credentials that were used during the initial installation.

To allow the cluster to use the new credentials, you must update the secrets that the Cloud Credential Operator (CCO) uses to manage cloud provider credentials.

6.14.1. Rotating cloud provider credentials with the Cloud Credential Operator utility

The Cloud Credential Operator (CCO) utility ccoctl supports updating secrets for clusters installed on IBM Cloud.

6.14.1.1. Rotating API keys for IBM Cloud

You can rotate API keys for your existing service IDs and update the corresponding secrets.

Prerequisites

  • You have configured the ccoctl binary.
  • You have existing service IDs in a live OpenShift Container Platform cluster installed on IBM Cloud.

Procedure

  • Use the ccoctl utility to rotate your API keys for the service IDs and update the secrets: 

    $ ccoctl ibmcloud refresh-keys \
    --kubeconfig <openshift_kubeconfig_file> \ 1
    --credentials-requests-dir <path_to_credential_requests_directory> \ 2
    --name <name> 3
    1
    The kubeconfig file associated with the cluster. For example, <installation_directory>/auth/kubeconfig.
    2
    The directory where the credential requests are stored.
    3
    The name of the OpenShift Container Platform cluster.
    Note

    If your cluster uses Technology Preview features that are enabled by the TechPreviewNoUpgrade feature set, you must include the --enable-tech-preview parameter.

6.14.2. Rotating cloud provider credentials manually

If your cloud provider credentials are changed for any reason, you must manually update the secret that the Cloud Credential Operator (CCO) uses to manage cloud provider credentials.

The process for rotating cloud credentials depends on the mode that the CCO is configured to use. After you rotate credentials for a cluster that is using mint mode, you must manually remove the component credentials that were created by the removed credential.

Prerequisites

  • Your cluster is installed on a platform that supports rotating cloud credentials manually with the CCO mode that you are using:

    • For mint mode, Amazon Web Services (AWS) and Google Cloud Platform (GCP) are supported.
    • For passthrough mode, Amazon Web Services (AWS), Microsoft Azure, Google Cloud Platform (GCP), Red Hat OpenStack Platform (RHOSP), Red Hat Virtualization (RHV), and VMware vSphere are supported.
  • You have changed the credentials that are used to interface with your cloud provider.
  • The new credentials have sufficient permissions for the mode CCO is configured to use in your cluster.

Procedure

  1. In the Administrator perspective of the web console, navigate to Workloads → Secrets.

  2. In the table on the Secrets page, find the root secret for your cloud provider.

    PlatformSecret name

    AWS

    aws-creds

    Azure

    azure-credentials

    GCP

    gcp-credentials

    RHOSP

    openstack-credentials

    RHV

    ovirt-credentials

    VMware vSphere

    vsphere-creds

  3. Click the Options menu kebab in the same row as the secret and select Edit Secret.
  4. Record the contents of the Value field or fields. You can use this information to verify that the value is different after updating the credentials.
  5. Update the text in the Value field or fields with the new authentication information for your cloud provider, and then click Save.

  6. If you are updating the credentials for a vSphere cluster that does not have the vSphere CSI Driver Operator enabled, you must force a rollout of the Kubernetes controller manager to apply the updated credentials.

    Note

    If the vSphere CSI Driver Operator is enabled, this step is not required.

    To apply the updated vSphere credentials, log in to the OpenShift Container Platform CLI as a user with the cluster-admin role and run the following command: 

    $ oc patch kubecontrollermanager cluster \
  -p='{"spec": {"forceRedeploymentReason": "recovery-'"$( date )"'"}}' \
  --type=merge

    While the credentials are rolling out, the status of the Kubernetes Controller Manager Operator reports Progressing=true. To view the status, run the following command: 

    $ oc get co kube-controller-manager

  7. If the CCO for your cluster is configured to use mint mode, delete each component secret that is referenced by the individual CredentialsRequest objects.

    1. Log in to the OpenShift Container Platform CLI as a user with the cluster-admin role.

    2. Get the names and namespaces of all referenced component secrets: 

      $ oc -n openshift-cloud-credential-operator get CredentialsRequest \
  -o json | jq -r '.items[] | select (.spec.providerSpec.kind=="<provider_spec>") | .spec.secretRef'

      where <provider_spec> is the corresponding value for your cloud provider:

      • AWS: AWSProviderSpec
      • GCP: GCPProviderSpec

      Partial example output for AWS

      {
  "name": "ebs-cloud-credentials",
  "namespace": "openshift-cluster-csi-drivers"
}
{
  "name": "cloud-credential-operator-iam-ro-creds",
  "namespace": "openshift-cloud-credential-operator"
}

    3. Delete each of the referenced component secrets: 

      $ oc delete secret <secret_name> \1
  -n <secret_namespace> 2
      1
      Specify the name of a secret.
      2
      Specify the namespace that contains the secret.

      Example deletion of an AWS secret

      $ oc delete secret ebs-cloud-credentials -n openshift-cluster-csi-drivers

      You do not need to manually delete the credentials from your provider console. Deleting the referenced component secrets will cause the CCO to delete the existing credentials from the platform and create new ones.

Verification

To verify that the credentials have changed:

  1. In the Administrator perspective of the web console, navigate to Workloads → Secrets.
  2. Verify that the contents of the Value field or fields have changed.

Additional resources

6.14.3. Removing cloud provider credentials

For clusters that use the Cloud Credential Operator (CCO) in mint mode, the administrator-level credential is stored in the kube-system namespace. The CCO uses the admin credential to process the CredentialsRequest objects in the cluster and create users for components with limited permissions.

After installing an OpenShift Container Platform cluster with the CCO in mint mode, you can remove the administrator-level credential secret from the kube-system namespace in the cluster. The CCO only requires the administrator-level credential during changes that require reconciling new or modified CredentialsRequest custom resources, such as minor cluster version updates.

Note

Before performing a minor version cluster update (for example, updating from OpenShift Container Platform 4.16 to 4.17), you must reinstate the credential secret with the administrator-level credential. If the credential is not present, the update might be blocked.

Prerequisites

  • Your cluster is installed on a platform that supports removing cloud credentials from the CCO. Supported platforms are AWS and GCP.

Procedure

  1. In the Administrator perspective of the web console, navigate to Workloads → Secrets.

  2. In the table on the Secrets page, find the root secret for your cloud provider.

    PlatformSecret name

    AWS

    aws-creds

    GCP

    gcp-credentials

  3. Click the Options menu kebab in the same row as the secret and select Delete Secret.

Additional resources

Chapter 7. Postinstallation node tasks

After installing OpenShift Container Platform, you can further expand and customize your cluster to your requirements through certain node tasks.

7.1. Adding