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Chapter 5. Expanding the cluster

After deploying an installer-provisioned OpenShift Container Platform cluster, you can use the following procedures to expand the number of worker nodes. Ensure that each prospective worker node meets the prerequisites.

Note

Expanding the cluster using RedFish Virtual Media involves meeting minimum firmware requirements. See Firmware requirements for installing with virtual media in the Prerequisites section for additional details when expanding the cluster using RedFish Virtual Media.

5.1. Preparing the bare metal node
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To expand your cluster, you must provide the node with the relevant IP address. This can be done with a static configuration, or with a DHCP (Dynamic Host Configuration protocol) server. When expanding the cluster using a DHCP server, each node must have a DHCP reservation.

Reserving IP addresses so they become static IP addresses

Some administrators prefer to use static IP addresses so that each node’s IP address remains constant in the absence of a DHCP server. To configure static IP addresses with NMState, see "Optional: Configuring host network interfaces in the install-config.yaml file" in the "Setting up the environment for an OpenShift installation" section for additional details.

Preparing the bare metal node requires executing the following procedure from the provisioner node.

Procedure

  1. Get the oc binary: 

    $ curl -s https://mirror.openshift.com/pub/openshift-v4/clients/ocp/$VERSION/openshift-client-linux-$VERSION.tar.gz | tar zxvf - oc
     
    $ sudo cp oc /usr/local/bin
  2. Power off the bare metal node by using the baseboard management controller (BMC), and ensure it is off.

  3. Retrieve the user name and password of the bare metal node’s baseboard management controller. Then, create base64 strings from the user name and password: 

    $ echo -ne "root" | base64
     
    $ echo -ne "password" | base64

  4. Create a configuration file for the bare metal node. Depending on whether you are using a static configuration or a DHCP server, use one of the following example bmh.yaml files, replacing values in the YAML to match your environment: 

    $ vim bmh.yaml

    • Static configuration bmh.yaml: 

      ---
apiVersion: v1
      1 
      
kind: Secret
metadata:
 name: openshift-worker-<num>-network-config-secret
      2 
      
 namespace: openshift-machine-api
type: Opaque
stringData:
 nmstate: |
      3 
      
  interfaces:
      4 
      
  - name: <nic1_name>
      5 
      
    type: ethernet
    state: up
    ipv4:
      address:
      - ip: <ip_address>
      6 
      
        prefix-length: 24
      enabled: true
  dns-resolver:
    config:
      server:
      - <dns_ip_address>
      7 
      
  routes:
    config:
    - destination: 0.0.0.0/0
      next-hop-address: <next_hop_ip_address>
      8 
      
      next-hop-interface: <next_hop_nic1_name>
      9 
      
---
apiVersion: v1
kind: Secret
metadata:
  name: openshift-worker-<num>-bmc-secret
      10 
      
  namespace: openshift-machine-api
type: Opaque
data:
  username: <base64_of_uid>
      11 
      
  password: <base64_of_pwd>
      12 
      
---
apiVersion: metal3.io/v1alpha1
kind: BareMetalHost
metadata:
  name: openshift-worker-<num>
      13 
      
  namespace: openshift-machine-api
spec:
  online: True
  bootMACAddress: <nic1_mac_address>
      14 
      
  bmc:
    address: <protocol>://<bmc_url>
      15 
      
    credentialsName: openshift-worker-<num>-bmc-secret
      16 
      
    disableCertificateVerification: True
      17 
      
    username: <bmc_username>
      18 
      
    password: <bmc_password>
      19 
      
  rootDeviceHints:
    deviceName: <root_device_hint>
      20 
      
  preprovisioningNetworkDataName: openshift-worker-<num>-network-config-secret
      21
      1
      To configure the network interface for a newly created node, specify the name of the secret that contains the network configuration. Follow the nmstate syntax to define the network configuration for your node. See "Optional: Configuring host network interfaces in the install-config.yaml file" for details on configuring NMState syntax.
      2 10 13 16
      Replace <num> for the worker number of the bare metal node in the name fields, the credentialsName field, and the preprovisioningNetworkDataName field.
      3
      Add the NMState YAML syntax to configure the host interfaces.
      4
      Optional: If you have configured the network interface with nmstate, and you want to disable an interface, set state: up with the IP addresses set to enabled: false as shown: 
      ---
   interfaces:
   - name: <nic_name>
     type: ethernet
     state: up
     ipv4:
       enabled: false
     ipv6:
       enabled: false
      5 6 7 8 9
      Replace <nic1_name>, <ip_address>, <dns_ip_address>, <next_hop_ip_address> and <next_hop_nic1_name> with appropriate values.
      11 12
      Replace <base64_of_uid> and <base64_of_pwd> with the base64 string of the user name and password.
      14
      Replace <nic1_mac_address> with the MAC address of the bare metal node’s first NIC. See the "BMC addressing" section for additional BMC configuration options.
      15
      Replace <protocol> with the BMC protocol, such as IPMI, RedFish, or others. Replace <bmc_url> with the URL of the bare metal node’s baseboard management controller.
      17
      To skip certificate validation, set disableCertificateVerification to true.
      18 19
      Replace <bmc_username> and <bmc_password> with the string of the BMC user name and password.
      20
      Optional: Replace <root_device_hint> with a device path if you specify a root device hint.
      21
      Optional: If you have configured the network interface for the newly created node, provide the network configuration secret name in the preprovisioningNetworkDataName of the BareMetalHost CR.

    • DHCP configuration bmh.yaml: 

      ---
apiVersion: v1
kind: Secret
metadata:
  name: openshift-worker-<num>-bmc-secret
      1 
      
  namespace: openshift-machine-api
type: Opaque
data:
  username: <base64_of_uid>
      2 
      
  password: <base64_of_pwd>
      3 
      
---
apiVersion: metal3.io/v1alpha1
kind: BareMetalHost
metadata:
  name: openshift-worker-<num>
      4 
      
  namespace: openshift-machine-api
spec:
  online: True
  bootMACAddress: <nic1_mac_address>
      5 
      
  bmc:
    address: <protocol>://<bmc_url>
      6 
      
    credentialsName: openshift-worker-<num>-bmc-secret
      7 
      
    disableCertificateVerification: True
      8 
      
    username: <bmc_username>
      9 
      
    password: <bmc_password>
      10 
      
  rootDeviceHints:
    deviceName: <root_device_hint>
      11 
      
  preprovisioningNetworkDataName: openshift-worker-<num>-network-config-secret
      12
      1 4 7
      Replace <num> for the worker number of the bare metal node in the name fields, the credentialsName field, and the preprovisioningNetworkDataName field.
      2 3
      Replace <base64_of_uid> and <base64_of_pwd> with the base64 string of the user name and password.
      5
      Replace <nic1_mac_address> with the MAC address of the bare metal node’s first NIC. See the "BMC addressing" section for additional BMC configuration options.
      6
      Replace <protocol> with the BMC protocol, such as IPMI, RedFish, or others. Replace <bmc_url> with the URL of the bare metal node’s baseboard management controller.
      8
      To skip certificate validation, set disableCertificateVerification to true.
      9 10
      Replace <bmc_username> and <bmc_password> with the string of the BMC user name and password.
      11
      Optional: Replace <root_device_hint> with a device path if you specify a root device hint.
      12
      Optional: If you have configured the network interface for the newly created node, provide the network configuration secret name in the preprovisioningNetworkDataName of the BareMetalHost CR.
    Note

    If the MAC address of an existing bare metal node matches the MAC address of a bare metal host that you are attempting to provision, then the Ironic installation will fail. If the host enrollment, inspection, cleaning, or other Ironic steps fail, the Bare Metal Operator retries the installation continuously. See "Diagnosing a host duplicate MAC address" for more information.

  5. Create the bare metal node: 

    $ oc -n openshift-machine-api create -f bmh.yaml

    Example output

    secret/openshift-worker-<num>-network-config-secret created
secret/openshift-worker-<num>-bmc-secret created
baremetalhost.metal3.io/openshift-worker-<num> created

    Where <num> will be the worker number.

  6. Power up and inspect the bare metal node: 

    $ oc -n openshift-machine-api get bmh openshift-worker-<num>

    Where <num> is the worker node number.

    Example output

    NAME                    STATE       CONSUMER   ONLINE   ERROR
openshift-worker-<num>  available              true

    Note

    To allow the worker node to join the cluster, scale the machineset object to the number of the BareMetalHost objects. You can scale nodes either manually or automatically. To scale nodes automatically, use the metal3.io/autoscale-to-hosts annotation for machineset.

5.2. Replacing a bare-metal control plane node
Copier lien

Use the following procedure to replace an installer-provisioned OpenShift Container Platform control plane node.

Important

If you reuse the BareMetalHost object definition from an existing control plane host, do not leave the externallyProvisioned field set to true.

Existing control plane BareMetalHost objects may have the externallyProvisioned flag set to true if they were provisioned by the OpenShift Container Platform installation program.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.

  • You have taken an etcd backup.

    Important

    Take an etcd backup before performing this procedure so that you can restore your cluster if you encounter any issues. For more information about taking an etcd backup, see the Additional resources section.

Procedure

  1. Ensure that the Bare Metal Operator is available: 

    $ oc get clusteroperator baremetal

    Example output

    NAME        VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE   MESSAGE
baremetal   4.18   True        False         False      3d15h

  2. Remove the old BareMetalHost and Machine objects: 

    $ oc delete bmh -n openshift-machine-api <host_name>
     
    $ oc delete machine -n openshift-machine-api <machine_name>

    Replace <host_name> with the name of the host and <machine_name> with the name of the machine. The machine name appears under the CONSUMER field.

    After you remove the BareMetalHost and Machine objects, then the machine controller automatically deletes the Node object.

  3. Create the new BareMetalHost object and the secret to store the BMC credentials: 

    $ cat <<EOF | oc apply -f -
apiVersion: v1
kind: Secret
metadata:
  name: control-plane-<num>-bmc-secret
    1 
    
  namespace: openshift-machine-api
data:
  username: <base64_of_uid>
    2 
    
  password: <base64_of_pwd>
    3 
    
type: Opaque
---
apiVersion: metal3.io/v1alpha1
kind: BareMetalHost
metadata:
  name: control-plane-<num>
    4 
    
  namespace: openshift-machine-api
spec:
  automatedCleaningMode: disabled
  bmc:
    address: <protocol>://<bmc_ip>
    5 
    
    credentialsName: control-plane-<num>-bmc-secret
    6 
    
  bootMACAddress: <NIC1_mac_address>
    7 
    
  bootMode: UEFI
  externallyProvisioned: false
  online: true
EOF
    1 4 6
    Replace <num> for the control plane number of the bare metal node in the name fields and the credentialsName field.
    2
    Replace <base64_of_uid> with the base64 string of the user name.
    3
    Replace <base64_of_pwd> with the base64 string of the password.
    5
    Replace <protocol> with the BMC protocol, such as redfish, redfish-virtualmedia, idrac-virtualmedia, or others. Replace <bmc_ip> with the IP address of the bare metal node’s baseboard management controller. For additional BMC configuration options, see "BMC addressing" in the Additional resources section.
    7
    Replace <NIC1_mac_address> with the MAC address of the bare metal node’s first NIC.

    After the inspection is complete, the BareMetalHost object is created and available to be provisioned.

  4. View available BareMetalHost objects: 

    $ oc get bmh -n openshift-machine-api

    Example output

    NAME                          STATE                    CONSUMER                   ONLINE   ERROR   AGE
control-plane-1.example.com   available                control-plane-1            true             1h10m
control-plane-2.example.com   externally provisioned   control-plane-2            true             4h53m
control-plane-3.example.com   externally provisioned   control-plane-3            true             4h53m
compute-1.example.com         provisioned              compute-1-ktmmx            true             4h53m
compute-1.example.com         provisioned              compute-2-l2zmb            true             4h53m

    There are no MachineSet objects for control plane nodes, so you must create a Machine object instead. You can copy the providerSpec from another control plane Machine object.

  5. Create a Machine object: 

    $ cat <<EOF | oc apply -f -
apiVersion: machine.openshift.io/v1beta1
kind: Machine
metadata:
  annotations:
    metal3.io/BareMetalHost: openshift-machine-api/control-plane-<num>
    1 
    
  labels:
    machine.openshift.io/cluster-api-cluster: control-plane-<num>
    2 
    
    machine.openshift.io/cluster-api-machine-role: master
    machine.openshift.io/cluster-api-machine-type: master
  name: control-plane-<num>
    3 
    
  namespace: openshift-machine-api
spec:
  metadata: {}
  providerSpec:
    value:
      apiVersion: baremetal.cluster.k8s.io/v1alpha1
      customDeploy:
        method: install_coreos
      hostSelector: {}
      image:
        checksum: ""
        url: ""
      kind: BareMetalMachineProviderSpec
      metadata:
        creationTimestamp: null
      userData:
        name: master-user-data-managed
EOF
    1 2 3
    Replace <num> for the control plane number of the bare metal node in the name, labels and annotations fields.

  6. To view the BareMetalHost objects, run the following command: 

    $ oc get bmh -A

    Example output

    NAME                          STATE                    CONSUMER                   ONLINE   ERROR   AGE
control-plane-1.example.com   provisioned              control-plane-1            true             2h53m
control-plane-2.example.com   externally provisioned   control-plane-2            true             5h53m
control-plane-3.example.com   externally provisioned   control-plane-3            true             5h53m
compute-1.example.com         provisioned              compute-1-ktmmx            true             5h53m
compute-2.example.com         provisioned              compute-2-l2zmb            true             5h53m

  7. After the RHCOS installation, verify that the BareMetalHost is added to the cluster: 

    $ oc get nodes

    Example output

    NAME                           STATUS      ROLES     AGE   VERSION
control-plane-1.example.com    available   master    4m2s  v1.31.3
control-plane-2.example.com    available   master    141m  v1.31.3
control-plane-3.example.com    available   master    141m  v1.31.3
compute-1.example.com          available   worker    87m   v1.31.3
compute-2.example.com          available   worker    87m   v1.31.3

    Note

    After replacement of the new control plane node, the etcd pod running in the new node is in crashloopback status. See "Replacing an unhealthy etcd member" in the Additional resources section for more information.

If the provisioning network is enabled and you want to expand the cluster using Virtual Media on the baremetal network, use the following procedure.

Prerequisites

  • There is an existing cluster with a baremetal network and a provisioning network.

Procedure

  1. Edit the provisioning custom resource (CR) to enable deploying with Virtual Media on the baremetal network: 

    oc edit provisioning
     
      apiVersion: metal3.io/v1alpha1
  kind: Provisioning
  metadata:
    creationTimestamp: "2021-08-05T18:51:50Z"
    finalizers:
    - provisioning.metal3.io
    generation: 8
    name: provisioning-configuration
    resourceVersion: "551591"
    uid: f76e956f-24c6-4361-aa5b-feaf72c5b526
  spec:
    provisioningDHCPRange: 172.22.0.10,172.22.0.254
    provisioningIP: 172.22.0.3
    provisioningInterface: enp1s0
    provisioningNetwork: Managed
    provisioningNetworkCIDR: 172.22.0.0/24
    virtualMediaViaExternalNetwork: true
    1 
    
  status:
    generations:
    - group: apps
      hash: ""
      lastGeneration: 7
      name: metal3
      namespace: openshift-machine-api
      resource: deployments
    - group: apps
      hash: ""
      lastGeneration: 1
      name: metal3-image-cache
      namespace: openshift-machine-api
      resource: daemonsets
    observedGeneration: 8
    readyReplicas: 0
    1
    Add virtualMediaViaExternalNetwork: true to the provisioning CR.

  2. If the image URL exists, edit the machineset to use the API VIP address. This step only applies to clusters installed in versions 4.9 or earlier. 

    oc edit machineset
     
      apiVersion: machine.openshift.io/v1beta1
  kind: MachineSet
  metadata:
    creationTimestamp: "2021-08-05T18:51:52Z"
    generation: 11
    labels:
      machine.openshift.io/cluster-api-cluster: ostest-hwmdt
      machine.openshift.io/cluster-api-machine-role: worker
      machine.openshift.io/cluster-api-machine-type: worker
    name: ostest-hwmdt-worker-0
    namespace: openshift-machine-api
    resourceVersion: "551513"
    uid: fad1c6e0-b9da-4d4a-8d73-286f78788931
  spec:
    replicas: 2
    selector:
      matchLabels:
        machine.openshift.io/cluster-api-cluster: ostest-hwmdt
        machine.openshift.io/cluster-api-machineset: ostest-hwmdt-worker-0
    template:
      metadata:
        labels:
          machine.openshift.io/cluster-api-cluster: ostest-hwmdt
          machine.openshift.io/cluster-api-machine-role: worker
          machine.openshift.io/cluster-api-machine-type: worker
          machine.openshift.io/cluster-api-machineset: ostest-hwmdt-worker-0
      spec:
        metadata: {}
        providerSpec:
          value:
            apiVersion: baremetal.cluster.k8s.io/v1alpha1
            hostSelector: {}
            image:
              checksum: http:/172.22.0.3:6181/images/rhcos-<version>.<architecture>.qcow2.<md5sum>
    1 
    
              url: http://172.22.0.3:6181/images/rhcos-<version>.<architecture>.qcow2
    2 
    
            kind: BareMetalMachineProviderSpec
            metadata:
              creationTimestamp: null
            userData:
              name: worker-user-data
  status:
    availableReplicas: 2
    fullyLabeledReplicas: 2
    observedGeneration: 11
    readyReplicas: 2
    replicas: 2
    1
    Edit the checksum URL to use the API VIP address.
    2
    Edit the url URL to use the API VIP address.

If the MAC address of an existing bare-metal node in the cluster matches the MAC address of a bare-metal host you are attempting to add to the cluster, the Bare Metal Operator associates the host with the existing node. If the host enrollment, inspection, cleaning, or other Ironic steps fail, the Bare Metal Operator retries the installation continuously. A registration error is displayed for the failed bare-metal host.

You can diagnose a duplicate MAC address by examining the bare-metal hosts that are running in the openshift-machine-api namespace.

Prerequisites

  • Install an OpenShift Container Platform cluster on bare metal.
  • Install the OpenShift Container Platform CLI oc.
  • Log in as a user with cluster-admin privileges.

Procedure

To determine whether a bare-metal host that fails provisioning has the same MAC address as an existing node, do the following:

  1. Get the bare-metal hosts running in the openshift-machine-api namespace: 

    $ oc get bmh -n openshift-machine-api

    Example output

    NAME                 STATUS   PROVISIONING STATUS      CONSUMER
openshift-master-0   OK       externally provisioned   openshift-zpwpq-master-0
openshift-master-1   OK       externally provisioned   openshift-zpwpq-master-1
openshift-master-2   OK       externally provisioned   openshift-zpwpq-master-2
openshift-worker-0   OK       provisioned              openshift-zpwpq-worker-0-lv84n
openshift-worker-1   OK       provisioned              openshift-zpwpq-worker-0-zd8lm
openshift-worker-2   error    registering

  2. To see more detailed information about the status of the failing host, run the following command replacing <bare_metal_host_name> with the name of the host: 

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

    Example output

    ...
status:
  errorCount: 12
  errorMessage: MAC address b4:96:91:1d:7c:20 conflicts with existing node openshift-worker-1
  errorType: registration error
...

5.5. Provisioning the bare metal node
Copier lien

Provisioning the bare metal node requires executing the following procedure from the provisioner node.

Procedure

  1. Ensure the STATE is available before provisioning the bare metal node. 

    $  oc -n openshift-machine-api get bmh openshift-worker-<num>

    Where <num> is the worker node number. 

    NAME              STATE     ONLINE ERROR  AGE
openshift-worker  available true          34h

  2. Get a count of the number of worker nodes. 

    $ oc get nodes
     
    NAME                                                STATUS   ROLES           AGE     VERSION
openshift-master-1.openshift.example.com            Ready    master          30h     v1.31.3
openshift-master-2.openshift.example.com            Ready    master          30h     v1.31.3
openshift-master-3.openshift.example.com            Ready    master          30h     v1.31.3
openshift-worker-0.openshift.example.com            Ready    worker          30h     v1.31.3
openshift-worker-1.openshift.example.com            Ready    worker          30h     v1.31.3

  3. Get the compute machine set. 

    $ oc get machinesets -n openshift-machine-api
     
    NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
...
openshift-worker-0.example.com      1         1         1       1           55m
openshift-worker-1.example.com      1         1         1       1           55m

  4. Increase the number of worker nodes by one. 

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

    Replace <num> with the new number of worker nodes. Replace <machineset> with the name of the compute machine set from the previous step.

  5. Check the status of the bare metal node. 

    $ oc -n openshift-machine-api get bmh openshift-worker-<num>

    Where <num> is the worker node number. The STATE changes from ready to provisioning. 

    NAME                    STATE             CONSUMER                          ONLINE   ERROR
openshift-worker-<num>  provisioning      openshift-worker-<num>-65tjz      true

    The provisioning status remains until the OpenShift Container Platform cluster provisions the node. This can take 30 minutes or more. After the node is provisioned, the state will change to provisioned. 

    NAME                    STATE             CONSUMER                          ONLINE   ERROR
openshift-worker-<num>  provisioned       openshift-worker-<num>-65tjz      true

  6. After provisioning completes, ensure the bare metal node is ready. 

    $ oc get nodes
     
    NAME                                          STATUS   ROLES   AGE     VERSION
openshift-master-1.openshift.example.com      Ready    master  30h     v1.31.3
openshift-master-2.openshift.example.com      Ready    master  30h     v1.31.3
openshift-master-3.openshift.example.com      Ready    master  30h     v1.31.3
openshift-worker-0.openshift.example.com      Ready    worker  30h     v1.31.3
openshift-worker-1.openshift.example.com      Ready    worker  30h     v1.31.3
openshift-worker-<num>.openshift.example.com  Ready    worker  3m27s   v1.31.3

    You can also check the kubelet. 

    $ ssh openshift-worker-<num>
     
    [kni@openshift-worker-<num>]$ journalctl -fu kubelet
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