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Windows Container Support for OpenShift

OpenShift Container Platform 4.8

Red Hat OpenShift for Windows Containers Guide

Red Hat OpenShift Documentation Team

Abstract

Red Hat OpenShift for Windows Containers provides built-in support for running Microsoft Windows Server containers on OpenShift Container Platform. This guide provides all the details.

Red Hat OpenShift support for Windows Containers is a feature providing the ability to run Windows compute nodes in an OpenShift Container Platform cluster. This is possible by using the Red Hat Windows Machine Config Operator (WMCO) to install and manage Windows nodes. With a Red Hat subscription, you can get support for running Windows workloads in OpenShift Container Platform. For more information, see the release notes.

For workloads including both Linux and Windows, OpenShift Container Platform allows you to deploy Windows workloads running on Windows Server containers while also providing traditional Linux workloads hosted on Red Hat Enterprise Linux CoreOS (RHCOS) or Red Hat Enterprise Linux (RHEL). For more information, see getting started with Windows container workloads.

You need the WMCO to run Windows workloads in your cluster. The WMCO orchestrates the process of deploying and managing Windows workloads on a cluster. For more information, see how to enable Windows container workloads.

You can create a Windows MachineSet object to create infrastructure Windows machine sets and related machines so that you can move supported Windows workloads to the new Windows machines. You can create a Windows MachineSet object on multiple platforms.

You can schedule Windows workloads to Windows compute nodes.

You can perform Windows Machine Config Operator upgrades to ensure that your Windows nodes have the latest updates.

You can remove a Windows node by deleting a specific machine.

You can use Bring-Your-Own-Host (BYOH) Windows instances to repurpose Windows Server VMs and bring them to OpenShift Container Platform. BYOH Windows instances benefit users who are looking to mitigate major disruptions in the event that a Windows server goes offline. You can use BYOH Windows instances as nodes on OpenShift Container Platform 4.8 and later versions.

You can disable Windows container workloads by performing the following:

  • Uninstalling the Windows Machine Config Operator
  • Deleting the Windows Machine Config Operator namespace

Red Hat OpenShift support for Windows Containers enables running Windows compute nodes in an OpenShift Container Platform cluster. Running Windows workloads is possible by using the Red Hat Windows Machine Config Operator (WMCO) to install and manage Windows nodes. With Windows nodes available, you can run Windows container workloads in OpenShift Container Platform.

The release notes for Red Hat OpenShift support for Windows Containers tracks the development of the WMCO, which provides all Windows container workload capabilities in OpenShift Container Platform.

2.2. Getting support
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Red Hat OpenShift support for Windows Containers is provided and available as an optional, installable component. Windows Container Support for Red Hat OpenShift is not part of the OpenShift Container Platform subscription. It requires an additional Red Hat subscription and is supported according to the Scope of coverage and Service level agreements.

You must have this separate subscription to receive support for Windows Container Support for Red Hat OpenShift. Without this additional Red Hat subscription, deploying Windows container workloads in production clusters is not supported. You can request support through the Red Hat Customer Portal.

For more information, see the Red Hat OpenShift Container Platform Life Cycle Policy document for Red Hat OpenShift support for Windows Containers.

If you do not have this additional Red Hat subscription, you can use the Community Windows Machine Config Operator, a distribution that lacks official support.

Issued: 2022-11-09

The WMCO 3.1.2 is now available with bug fixes. The components of the WMCO were released in RHBA-2022:7076.

2.3.1. Bug fixes
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  • Previously, Windows containers on Windows nodes were assigned the wrong DNS Server IP if a non-default cluster DNS was specified during the cluster installation. Therefore, the DNS resolution did not work. This bug fix removes the hard-coded cluster DNS information and parametrizes the value as a command-line argument. (BZ#2030943)

Issued: 2021-12-07

The WMCO 3.1.1 is now available with bug fixes. The components of the WMCO were released in RHBA-2021:4710.

2.4.1. Bug fixes
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  • Previously, the windows-exporter metrics endpoint object contained a reference to a deleted machine. This incorrect reference caused the WMCO to ignore deleted events for machines with invalid IP addresses. This bug fix removes the validation of the machine object from the event filtering, allowing the windows-exporter metrics endpoint object to correctly update when the machine is still in the Deleting phase. (BZ#2008994)
  • Previously, deleting the node associated with a Windows Machine object threw a reconciliation error upon restart of the Operator. This bug fix opts not to react or reconcile when the node referenced by a Windows machine in the Running state is not found within the cluster, preventing any error loop and standardizing functionality with Linux machine objects. (BZ#2009475)
  • Previously, the WMCO did not properly associate BYOH Windows VMs with their Node object when the VM was specified with a DNS object. This caused the WMCO to attempt to configure VMs that were already fully configured. The WMCO now correctly resolves VMs specified by a DNS address when looking for an associated node. (BZ#2020650)
  • Previously, encrypted usernames were being generated with extra tags, which caused them not to display correctly. This bug fix removes the extra tags, allowing the encrypted username to display correctly. (BZ#2023417)
  • Previously, certain commands being run by the WMCO in Windows VMs were not parsed correctly by PowerShell. This caused Windows VMs with PowerShell as its default SSH shell to be unable to join to a cluster as a node. The WMCO can now identify the default SSH shell of a Windows VM and run the associated commands accordingly. This new capability allows Windows VMs with PowerShell as the default SSH shell to be configured as nodes in a cluster. (BZ#2025730)

Issued: 2021-09-21

The WMCO 3.1.0 is now available with bug fixes and a new feature. The components of the WMCO were released in RHBA-2021:3215.

2.5.1. New features
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You can now add an existing Windows instance to an OpenShift Container Platform cluster as a compute node. This requires creating a config map in the WMCO namespace.

BYOH Windows instances are supported with installer-provisioned infrastructure for the following platforms:

  • Amazon Web Services (AWS)
  • Microsoft Azure
  • VMware vSphere

BYOH Windows instances are supported with user-provisioned infrastructure, only when the platform: none field is set in the install-config.yaml file, for the following platforms:

  • VMware vSphere
  • bare metal

For more information on how to configure BYOH Windows instances, see Configuring BYOH Windows instance.

2.5.2. Bug fixes
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  • For clusters installed on VMware vSphere, the WMCO ignored the Deleting phase notification event, leaving incorrect node information in the windows-exporter metrics endpoint. This resulted in an invalid mapping for the Prometheus metrics endpoint. This bug has been fixed; the WMCO now recognizes the Deleting phase notification event and maps the Prometheus metrics endpoint appropriately. (BZ#1995341)

2.5.3. Known issues
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  • When installing a BYOH Windows instance using a DNS name entry in the config map, the WMCO configures the instance twice before marking it as a Ready node. This will be fixed in a future release of the WMCO. (BZ#2005360)

  • When the RunAsUser permission is set in the security context of a Linux-based pod, the projected files have the correct permissions set, including container user ownership. However, when the Windows equivalent RunAsUsername permission is set in a Windows pod, the kubelet is prevented from setting correct ownership on the files in the projected volume. This problem can get exacerbated when used in conjunction with a hostPath volume where best practices are not followed. For example, giving a pod access to the C:\var\lib\kubelet\pods\ folder results in that pod being able to access service account tokens from other pods.

    By default, the projected files will have the following ownership, as shown in this example Windows projected volume file: 

    Path   : Microsoft.PowerShell.Core\FileSystem::C:\var\run\secrets\kubernetes.io\serviceaccount\..2021_08_31_22_22_18.318230061\ca.crt
Owner  : BUILTIN\Administrators
Group  : NT AUTHORITY\SYSTEM
Access : NT AUTHORITY\SYSTEM Allow  FullControl
         BUILTIN\Administrators Allow  FullControl
         BUILTIN\Users Allow  ReadAndExecute, Synchronize
Audit  :
Sddl   : O:BAG:SYD:AI(A;ID;FA;;;SY)(A;ID;FA;;;BA)(A;ID;0x1200a9;;;BU)
    Copy to Clipboard Toggle word wrap

    This indicates all administrator users, such as someone with the ContainerAdministrator role, have read, write, and execute access, while non-administrator users have read and execute access.

    Important

    OpenShift Container Platform applies the RunAsUser security context to all pods irrespective of its operating system. This means Windows pods automatically have the RunAsUser permission applied to its security context.

    In addition, if a Windows pod is created with a projected volume with the default RunAsUser permission set, the pod remains in the ContainerCreating phase.

    To handle these issues, OpenShift Container Platform forces the file permission handling in projected service account volumes set in the security context of the pod to not be honored for projected volumes on Windows. Note that this behavior for Windows pods is how file permission handling used to work for all pod types prior to OpenShift Container Platform 4.7. (BZ#1971745)

This release of the WMCO provides bug fixes and enhancements for running Windows compute nodes in an OpenShift Container Platform cluster. The components of the WMCO 3.0.0 were released in RHSA-2021:3001.

Important

Users running WMCO 2.0.2 and below must uninstall the operator and reinstall WMCO 3.0.0 to work around a known issue that prevents users from upgrading from WMCO 2.0.2 to WMCO 3.0.0. (BZ#1983153)

2.7. Windows Machine Config Operator prerequisites
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The following information details the supported platform versions, Windows Server versions, and networking configurations for the Windows Machine Config Operator. See the vSphere documentation for any information that is relevant to only that platform.

Expand
PlatformSupported OpenShift Container Platform versionSupported WMCO versionInstaller-provisioned infrastructure installation supportUser-provisioned infrastructure installation support

Amazon Web Services (AWS)

4.6+

WMCO 1.0+

GA

Tech Preview

Microsoft Azure

4.6+

WMCO 1.0+

GA

Tech Preview

VMware vSphere

4.7+

WMCO 2.0+

GA

Tech Preview

Expand
PlatformSupported OpenShift Container Platform versionSupported WMCO versionBYOH for installer-provisioned infrastructure installation supportBYOH for user-provisioned infrastructure installation support

Amazon Web Services (AWS)

4.8+

WMCO 3.1+

GA

Tech Preview

Microsoft Azure

4.8+

WMCO 3.1+

GA

Tech Preview

VMware vSphere

4.8+

WMCO 3.1+

GA

GA[1]

bare metal

4.8+

WMCO 3.1+

 

GA[1]

  1. This installation type is only supported when the platform: none field is set in the install-config.yaml file during cluster installation.

2.7.3. Supported Windows Server versions
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The following table lists the supported Windows Server version based on the applicable platform. Any unlisted Windows Server version is not supported and will cause errors. To prevent these errors, only use the appropriate version according to the platform in use.

Expand
PlatformSupported Windows Server version

Amazon Web Services (AWS)

Windows Server 2019, version 1809

Microsoft Azure

Windows Server 2019, version 1809

VMware vSphere

Windows Server 2022, OS Build 20348.681 or later

Note

Windows Server 2019 is unsupported, because the KB4565351 patch is not included.

bare metal

Windows Server 2019, version 1809

2.7.4. Supported networking
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Hybrid networking with OVN-Kubernetes is the only supported networking configuration. See the additional resources below for more information on this functionality. The following tables outline the type of networking configuration and Windows Server versions to use based on your platform. You must specify the network configuration when you install the cluster. Be aware that OpenShift SDN networking is the default network for OpenShift Container Platform clusters. However, OpenShift SDN is not supported by WMCO.

Expand
Table 2.1. Platform networking support
PlatformSupported networking

Amazon Web Services (AWS)

Hybrid networking with OVN-Kubernetes

Microsoft Azure

Hybrid networking with OVN-Kubernetes

VMware vSphere

Hybrid networking with OVN-Kubernetes with a custom VXLAN port

bare metal

Hybrid networking with OVN-Kubernetes

Expand
Table 2.2. Hybrid OVN-Kubernetes Windows Server support
Hybrid networking with OVN-KubernetesSupported Windows Server version

Default VXLAN port

Windows Server 2019, version 1809

Custom VXLAN port

Windows Server 2022, OS Build 20348.681 or later

Important

Running Windows container workloads is not supported for clusters in a restricted network or disconnected environment.

Version 3.x of the WMCO is only compatible with OpenShift Container Platform 4.8.

2.7.5. New features and improvements
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This release adds the following new features and improvements.

Users must not select a custom VXLAN port when using the latest version of Windows server.

2.7.6. Bug fixes
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  • Previously, the load balancer service would become unstable when the backing deployment had multiple pods scheduled on different Windows nodes. This issue has been fixed. (BZ#1905950)
  • Previously, WMCO added the public key annotation windowsmachineconfig.openshift.io/pub-key-hash to Linux nodes. Now, WMCO no longer adds an annotation to Linux nodes. (BZ#1930791)
  • Previously, when users provided an invalid private key, the WMCO would fail. With this update, the WMCO produces an error alerting the user of an invalid key. (BZ#1929579)
  • Previously, the kube-proxy service would crash upon the creation of a load balancer service when the backing development had multiple pods scheduled on different Windows nodes. This issue has now been fixed. (BZ#1939968)
  • Previously, the windows_exporter component reported various metrics as windows_*. This error caused some of the node-level metrics that provide insight into the nodes through telemetry services to go unreported. Now, the components export correctly showing all of the expected metrics. (BZ#1948037)

As part of the previously noted bug fix (BZ#1946538), an update for Windows kube-proxy is now available for Red Hat Windows Machine Config Operator 2.0.1. Details of the update are documented in the RHSA-2021:2130 advisory.

2.8. Known issues
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  • The file system graphs available in the web console do not display for Windows nodes. This is caused by changes in the file system queries. This will be fixed in a future release of WMCO. (BZ#1930347)
  • When installing a BYOH Windows instance using a DNS name entry in the config map, the WMCO configures the instance twice before marking it as a Ready node. This will be fixed in a future release of the WMCO. (BZ#2005360)

2.9. Known limitations
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Note the following limitations when working with Windows nodes managed by the WMCO (Windows nodes):

  • The following OpenShift Container Platform features are not supported on Windows nodes:

    • Red Hat OpenShift Developer CLI (odo)
    • Image builds
    • OpenShift Pipelines
    • OpenShift Service Mesh
    • OpenShift monitoring of user-defined projects
    • OpenShift Serverless
    • Horizontal Pod Autoscaling
    • Vertical Pod Autoscaling

  • The following Red Hat features are not supported on Windows nodes:

  • Windows nodes do not support pulling container images from private registries. You can use images from public registries or pre-pull the images.
  • Windows nodes do not support workloads created by using deployment configs. You can use a deployment or other method to deploy workloads.
  • Windows nodes are not supported in clusters that use a cluster-wide proxy. This is because the WMCO is not able to route traffic through the proxy connection for the workloads.
  • Windows nodes are not supported in clusters that are in a disconnected environment.
  • Red Hat OpenShift support for Windows Containers does not support adding Windows nodes to a cluster through a trunk port. The only supported networking configuration for adding Windows nodes is through an access port that carries traffic for the VLAN.
  • Red Hat OpenShift support for Windows Containers supports only in-tree storage drivers for all cloud providers.

  • Kubernetes has identified the following node feature limitations :

    • Huge pages are not supported for Windows containers.
    • Privileged containers are not supported for Windows containers.
    • Pod termination grace periods require the containerd container runtime to be installed on the Windows node.
  • Kubernetes has identified several API compatibility issues.

Red Hat OpenShift support for Windows Containers provides built-in support for running Microsoft Windows Server containers on OpenShift Container Platform. For those that administer heterogeneous environments with a mix of Linux and Windows workloads, OpenShift Container Platform allows you to deploy Windows workloads running on Windows Server containers while also providing traditional Linux workloads hosted on Red Hat Enterprise Linux CoreOS (RHCOS) or Red Hat Enterprise Linux (RHEL).

Note

Multi-tenancy for clusters that have Windows nodes is not supported. Hostile multi-tenant usage introduces security concerns in all Kubernetes environments. Additional security features like pod security policies, or more fine-grained role-based access control (RBAC) for nodes, make exploits more difficult. However, if you choose to run hostile multi-tenant workloads, a hypervisor is the only security option you should use. The security domain for Kubernetes encompasses the entire cluster, not an individual node. For these types of hostile multi-tenant workloads, you should use physically isolated clusters.

Windows Server Containers provide resource isolation using a shared kernel but are not intended to be used in hostile multitenancy scenarios. Scenarios that involve hostile multitenancy should use Hyper-V Isolated Containers to strongly isolate tenants.

3.1. Windows Machine Config Operator prerequisites
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The following information details the supported platform versions, Windows Server versions, and networking configurations for the Windows Machine Config Operator. See the vSphere documentation for any information that is relevant to only that platform.

Expand
PlatformSupported OpenShift Container Platform versionSupported WMCO versionInstaller-provisioned infrastructure installation supportUser-provisioned infrastructure installation support

Amazon Web Services (AWS)

4.6+

WMCO 1.0+

GA

Tech Preview

Microsoft Azure

4.6+

WMCO 1.0+

GA

Tech Preview

VMware vSphere

4.7+

WMCO 2.0+

GA

Tech Preview

Expand
PlatformSupported OpenShift Container Platform versionSupported WMCO versionBYOH for installer-provisioned infrastructure installation supportBYOH for user-provisioned infrastructure installation support

Amazon Web Services (AWS)

4.8+

WMCO 3.1+

GA

Tech Preview

Microsoft Azure

4.8+

WMCO 3.1+

GA

Tech Preview

VMware vSphere

4.8+

WMCO 3.1+

GA

GA[1]

bare metal

4.8+

WMCO 3.1+

 

GA[1]

  1. This installation type is only supported when the platform: none field is set in the install-config.yaml file during cluster installation.

3.1.3. Supported Windows Server versions
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The following table lists the supported Windows Server version based on the applicable platform. Any unlisted Windows Server version is not supported and will cause errors. To prevent these errors, only use the appropriate version according to the platform in use.

Expand
PlatformSupported Windows Server version

Amazon Web Services (AWS)

Windows Server 2019, version 1809

Microsoft Azure

Windows Server 2019, version 1809

VMware vSphere

Windows Server 2022, OS Build 20348.681 or later

Note

Windows Server 2019 is unsupported, because the KB4565351 patch is not included.

bare metal

Windows Server 2019, version 1809

3.1.4. Supported networking
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Hybrid networking with OVN-Kubernetes is the only supported networking configuration. See the additional resources below for more information on this functionality. The following tables outline the type of networking configuration and Windows Server versions to use based on your platform. You must specify the network configuration when you install the cluster. Be aware that OpenShift SDN networking is the default network for OpenShift Container Platform clusters. However, OpenShift SDN is not supported by WMCO.

Expand
Table 3.1. Platform networking support
PlatformSupported networking

Amazon Web Services (AWS)

Hybrid networking with OVN-Kubernetes

Microsoft Azure

Hybrid networking with OVN-Kubernetes

VMware vSphere

Hybrid networking with OVN-Kubernetes with a custom VXLAN port

bare metal

Hybrid networking with OVN-Kubernetes

Expand
Table 3.2. Hybrid OVN-Kubernetes Windows Server support
Hybrid networking with OVN-KubernetesSupported Windows Server version

Default VXLAN port

Windows Server 2019, version 1809

Custom VXLAN port

Windows Server 2022, OS Build 20348.681 or later

3.2. Windows workload management
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To run Windows workloads in your cluster, you must first install the Windows Machine Config Operator (WMCO). The WMCO is a Linux-based Operator that runs on Linux-based control plane and compute nodes. The WMCO orchestrates the process of deploying and managing Windows workloads on a cluster.

Figure 3.1. WMCO design

WMCO workflow
View larger image
WMCO workflow

Before deploying Windows workloads, you must create a Windows compute node and have it join the cluster. The Windows node hosts the Windows workloads in a cluster, and can run alongside other Linux-based compute nodes. You can create a Windows compute node by creating a Windows machine set to host Windows Server compute machines. You must apply a Windows-specific label to the machine set that specifies a Windows OS image that has the Docker-formatted container runtime add-on enabled.

Important

Currently, the Docker-formatted container runtime is used in Windows nodes. Kubernetes is deprecating Docker as a container runtime; you can reference the Kubernetes documentation for more information in Docker deprecation. Containerd will be the new supported container runtime for Windows nodes in a future release of Kubernetes.

The WMCO watches for machines with the Windows label. After a Windows machine set is detected and its respective machines are provisioned, the WMCO configures the underlying Windows virtual machine (VM) so that it can join the cluster as a compute node.

Figure 3.2. Mixed Windows and Linux workloads

Mixed Windows and Linux workloads
View larger image
Mixed Windows and Linux workloads

The WMCO expects a predetermined secret in its namespace containing a private key that is used to interact with the Windows instance. WMCO checks for this secret during boot up time and creates a user data secret which you must reference in the Windows MachineSet object that you created. Then the WMCO populates the user data secret with a public key that corresponds to the private key. With this data in place, the cluster can connect to the Windows VM using an SSH connection.

After the cluster establishes a connection with the Windows VM, you can manage the Windows node using similar practices as you would a Linux-based node.

Note

The OpenShift Container Platform web console provides most of the same monitoring capabilities for Windows nodes that are available for Linux nodes. However, the ability to monitor workload graphs for pods running on Windows nodes is not available at this time.

Scheduling Windows workloads to a Windows node can be done with typical pod scheduling practices like taints, tolerations, and node selectors; alternatively, you can differentiate your Windows workloads from Linux workloads and other Windows-versioned workloads by using a RuntimeClass object.

3.3. Windows node services
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The following Windows-specific services are installed on each Windows node:

Expand
ServiceDescription

kubelet

Registers the Windows node and manages its status.

Container Network Interface (CNI) plugins

Exposes networking for Windows nodes.

Windows Machine Config Bootstrapper (WMCB)

Configures the kubelet and CNI plugins.

Windows Exporter

Exports Prometheus metrics from Windows nodes

hybrid-overlay

Creates the OpenShift Container Platform Host Network Service (HNS).

kube-proxy

Maintains network rules on nodes allowing outside communication.

3.4. Known limitations
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Note the following limitations when working with Windows nodes managed by the WMCO (Windows nodes):

  • The following OpenShift Container Platform features are not supported on Windows nodes:

    • Red Hat OpenShift Developer CLI (odo)
    • Image builds
    • OpenShift Pipelines
    • OpenShift Service Mesh
    • OpenShift monitoring of user-defined projects
    • OpenShift Serverless
    • Horizontal Pod Autoscaling
    • Vertical Pod Autoscaling

  • The following Red Hat features are not supported on Windows nodes:

  • Windows nodes do not support pulling container images from private registries. You can use images from public registries or pre-pull the images.
  • Windows nodes do not support workloads created by using deployment configs. You can use a deployment or other method to deploy workloads.
  • Windows nodes are not supported in clusters that use a cluster-wide proxy. This is because the WMCO is not able to route traffic through the proxy connection for the workloads.
  • Windows nodes are not supported in clusters that are in a disconnected environment.
  • Red Hat OpenShift support for Windows Containers does not support adding Windows nodes to a cluster through a trunk port. The only supported networking configuration for adding Windows nodes is through an access port that carries traffic for the VLAN.
  • Red Hat OpenShift support for Windows Containers supports only in-tree storage drivers for all cloud providers.

  • Kubernetes has identified the following node feature limitations :

    • Huge pages are not supported for Windows containers.
    • Privileged containers are not supported for Windows containers.
    • Pod termination grace periods require the containerd container runtime to be installed on the Windows node.
  • Kubernetes has identified several API compatibility issues.

Chapter 4. Enabling Windows container workloads
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Before adding Windows workloads to your cluster, you must install the Windows Machine Config Operator (WMCO), which is available in the OpenShift Container Platform OperatorHub. The WMCO orchestrates the process of deploying and managing Windows workloads on a cluster.

Note

Dual NIC is not supported on WMCO-managed Windows instances.

Prerequisites

  • You have access to an OpenShift Container Platform cluster using an account with cluster-admin permissions.
  • You have installed the OpenShift CLI (oc).
  • You have installed your cluster using installer-provisioned infrastructure, or using user-provisioned infrastructure with the platform: none field set in your install-config.yaml file.
  • You have configured hybrid networking with OVN-Kubernetes for your cluster. This must be completed during the installation of your cluster. For more information, see Configuring hybrid networking.
  • You are running an OpenShift Container Platform cluster version 4.6.8 or later.
Note

The WMCO is not supported in clusters that use a cluster-wide proxy because the WMCO is not able to route traffic through the proxy connection for the workloads.

You can install the Windows Machine Config Operator using either the web console or OpenShift CLI (oc).

You can use the OpenShift Container Platform web console to install the Windows Machine Config Operator (WMCO).

Note

Dual NIC is not supported on WMCO-managed Windows instances.

Procedure

  1. From the Administrator perspective in the OpenShift Container Platform web console, navigate to the Operators → OperatorHub page.
  2. Use the Filter by keyword box to search for Windows Machine Config Operator in the catalog. Click the Windows Machine Config Operator tile.
  3. Review the information about the Operator and click Install.

  4. On the Install Operator page:

    1. Select the stable channel as the Update Channel. The stable channel enables the latest stable release of the WMCO to be installed.
    2. The Installation Mode is preconfigured because the WMCO must be available in a single namespace only.
    3. Choose the Installed Namespace for the WMCO. The default Operator recommended namespace is openshift-windows-machine-config-operator.
    4. Click the Enable Operator recommended cluster monitoring on the Namespace checkbox to enable cluster monitoring for the WMCO.

    5. Select an Approval Strategy.

      • The Automatic strategy allows Operator Lifecycle Manager (OLM) to automatically update the Operator when a new version is available.
      • The Manual strategy requires a user with appropriate credentials to approve the Operator update.

  1. Click Install. The WMCO is now listed on the Installed Operators page.

    Note

    The WMCO is installed automatically into the namespace you defined, like openshift-windows-machine-config-operator.

  2. Verify that the Status shows Succeeded to confirm successful installation of the WMCO.

You can use the OpenShift CLI (oc) to install the Windows Machine Config Operator (WMCO).

Note

Dual NIC is not supported on WMCO-managed Windows instances.

Procedure

  1. Create a namespace for the WMCO.

    1. Create a Namespace object YAML file for the WMCO. For example, wmco-namespace.yaml: 

      apiVersion: v1
kind: Namespace
metadata:
  name: openshift-windows-machine-config-operator
      1 
      
  labels:
    openshift.io/cluster-monitoring: "true"
      2
      Copy to Clipboard Toggle word wrap
      1
      It is recommended to deploy the WMCO in the openshift-windows-machine-config-operator namespace.
      2
      This label is required for enabling cluster monitoring for the WMCO.

    2. Create the namespace: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f wmco-namespace.yaml
      Copy to Clipboard Toggle word wrap

  2. Create the Operator group for the WMCO.

    1. Create an OperatorGroup object YAML file. For example, wmco-og.yaml: 

      apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name: windows-machine-config-operator
  namespace: openshift-windows-machine-config-operator
spec:
  targetNamespaces:
  - openshift-windows-machine-config-operator
      Copy to Clipboard Toggle word wrap

    2. Create the Operator group: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f wmco-og.yaml
      Copy to Clipboard Toggle word wrap

  3. Subscribe the namespace to the WMCO.

    1. Create a Subscription object YAML file. For example, wmco-sub.yaml: 

      apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: windows-machine-config-operator
  namespace: openshift-windows-machine-config-operator
spec:
  channel: "stable"
      1 
      
  installPlanApproval: "Automatic"
      2 
      
  name: "windows-machine-config-operator"
  source: "redhat-operators"
      3 
      
  sourceNamespace: "openshift-marketplace"
      4
      Copy to Clipboard Toggle word wrap
      1
      Specify stable as the channel.
      2
      Set an approval strategy. You can set Automatic or Manual.
      3
      Specify the redhat-operators catalog source, which contains the windows-machine-config-operator package manifests. If your OpenShift Container Platform is installed on a restricted network, also known as a disconnected cluster, specify the name of the CatalogSource object you created when you configured the Operator LifeCycle Manager (OLM).
      4
      Namespace of the catalog source. Use openshift-marketplace for the default OperatorHub catalog sources.

    2. Create the subscription: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f wmco-sub.yaml
      Copy to Clipboard Toggle word wrap

      The WMCO is now installed to the openshift-windows-machine-config-operator.

  4. Verify the WMCO installation: 

    $ oc get csv -n openshift-windows-machine-config-operator
    Copy to Clipboard Toggle word wrap

    Example output

    NAME                                    DISPLAY                           VERSION   REPLACES   PHASE
windows-machine-config-operator.2.0.0   Windows Machine Config Operator   2.0.0                Succeeded
    Copy to Clipboard Toggle word wrap

To run the Windows Machine Config Operator (WMCO), you must create a secret in the WMCO namespace containing a private key. This is required to allow the WMCO to communicate with the Windows virtual machine (VM).

Prerequisites

  • You installed the Windows Machine Config Operator (WMCO) using Operator Lifecycle Manager (OLM).
  • You created a PEM-encoded file containing an RSA key.

Procedure

  • Define the secret required to access the Windows VMs: 

    $ oc create secret generic cloud-private-key --from-file=private-key.pem=${HOME}/.ssh/<key> \
    -n openshift-windows-machine-config-operator
    1
    Copy to Clipboard Toggle word wrap
1
You must create the private key in the WMCO namespace, like openshift-windows-machine-config-operator.

It is recommended to use a different private key than the one used when installing the cluster.

Chapter 5. Creating Windows MachineSet objects
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5.1. Creating a Windows MachineSet object on AWS
Copy link

You can create a Windows MachineSet object to serve a specific purpose in your OpenShift Container Platform cluster on Amazon Web Services (AWS). For example, you might create infrastructure Windows machine sets and related machines so that you can move supporting Windows workloads to the new Windows machines.

Prerequisites
  • You installed the Windows Machine Config Operator (WMCO) using Operator Lifecycle Manager (OLM).

  • You are using a supported Windows Server as the operating system image with the Docker-formatted container runtime add-on enabled.

    Use the following aws command to query valid AMI images: 

    $ aws ec2 describe-images --region <aws region name> --filters "Name=name,Values=Windows_Server-2019*English*Full*Containers*" "Name=is-public,Values=true" --query "reverse(sort_by(Images, &CreationDate))[*].{name: Name, id: ImageId}" --output table
    Copy to Clipboard Toggle word wrap
    Important

    Currently, the Docker-formatted container runtime is used in Windows nodes. Kubernetes is deprecating Docker as a container runtime; you can reference the Kubernetes documentation for more information in Docker deprecation. Containerd will be the new supported container runtime for Windows nodes in a future release of Kubernetes.

5.1.1. Machine API overview
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The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.8 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.8 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets

MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

Warning

Control plane machines cannot be managed by machine sets.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

This sample YAML defines a Windows MachineSet object running on Amazon Web Services (AWS) that the Windows Machine Config Operator (WMCO) can react upon. 

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id>
1 

  name: <infrastructure_id>-windows-worker-<zone>
2 

  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
3 

      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-windows-worker-<zone>
4 

  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
5 

        machine.openshift.io/cluster-api-machine-role: worker
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-windows-worker-<zone>
6 

        machine.openshift.io/os-id: Windows
7 

    spec:
      metadata:
        labels:
          node-role.kubernetes.io/worker: ""
8 

      providerSpec:
        value:
          ami:
            id: <windows_container_ami>
9 

          apiVersion: awsproviderconfig.openshift.io/v1beta1
          blockDevices:
            - ebs:
                iops: 0
                volumeSize: 120
                volumeType: gp2
          credentialsSecret:
            name: aws-cloud-credentials
          deviceIndex: 0
          iamInstanceProfile:
            id: <infrastructure_id>-worker-profile
10 

          instanceType: m5a.large
          kind: AWSMachineProviderConfig
          placement:
            availabilityZone: <zone>
11 

            region: <region>
12 

          securityGroups:
            - filters:
                - name: tag:Name
                  values:
                    - <infrastructure_id>-worker-sg
13 

          subnet:
            filters:
              - name: tag:Name
                values:
                  - <infrastructure_id>-private-<zone>
14 

          tags:
            - name: kubernetes.io/cluster/<infrastructure_id>
15 

              value: owned
          userDataSecret:
            name: windows-user-data
16 

            namespace: openshift-machine-api
Copy to Clipboard Toggle word wrap
1 3 5 10 13 14 15
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. You can obtain the infrastructure ID by running the following command: 
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
Copy to Clipboard Toggle word wrap
2 4 6
Specify the infrastructure ID, worker label, and zone.
7
Configure the machine set as a Windows machine.
8
Configure the Windows node as a compute machine.
9
Specify the AMI ID of a Windows image with a container runtime installed. You must use Windows Server 2019.
11
Specify the AWS zone, like us-east-1a.
12
Specify the AWS region, like us-east-1.
16
Created by the WMCO when it is configuring the first Windows machine. After that, the windows-user-data is available for all subsequent machine sets to consume.

5.1.3. Creating a machine set
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In addition to the ones created by the installation program, you can create your own machine sets 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 machine set custom resource (CR) sample and is named <file_name>.yaml.

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

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

      $ oc get machinesets -n openshift-machine-api
      Copy to Clipboard Toggle word wrap

      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
      Copy to Clipboard Toggle word wrap

    2. Check values of a specific machine set: 

      $ oc get machineset <machineset_name> -n \
     openshift-machine-api -o yaml
      Copy to Clipboard Toggle word wrap

      Example output

      ...
template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: agl030519-vplxk
      1 
      
        machine.openshift.io/cluster-api-machine-role: worker
      2 
      
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a
      Copy to Clipboard Toggle word wrap

      1
      The cluster ID.
      2
      A default node label.

  2. Create the new MachineSet CR: 

    $ oc create -f <file_name>.yaml
    Copy to Clipboard Toggle word wrap

  3. View the list of machine sets: 

    $ oc get machineset -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

    Example output

    NAME                                      DESIRED   CURRENT   READY   AVAILABLE   AGE
agl030519-vplxk-windows-worker-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
    Copy to Clipboard Toggle word wrap

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

5.2. Creating a Windows MachineSet object on Azure
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You can create a Windows MachineSet object to serve a specific purpose in your OpenShift Container Platform cluster on Microsoft Azure. For example, you might create infrastructure Windows machine sets and related machines so that you can move supporting Windows workloads to the new Windows machines.

Prerequisites
  • You installed the Windows Machine Config Operator (WMCO) using Operator Lifecycle Manager (OLM).
  • You are using a supported Windows Server as the operating system image with the Docker-formatted container runtime add-on enabled.
Important

Currently, the Docker-formatted container runtime is used in Windows nodes. Kubernetes is deprecating Docker as a container runtime; you can reference the Kubernetes documentation for more information in Docker deprecation. Containerd will be the new supported container runtime for Windows nodes in a future release of Kubernetes.

5.2.1. Machine API overview
Copy link

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.8 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.8 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets

MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

Warning

Control plane machines cannot be managed by machine sets.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

This sample YAML defines a Windows MachineSet object running on Microsoft Azure that the Windows Machine Config Operator (WMCO) can react upon. 

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id>
1 

  name: <windows_machine_set_name>
2 

  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
3 

      machine.openshift.io/cluster-api-machineset: <windows_machine_set_name>
4 

  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
5 

        machine.openshift.io/cluster-api-machine-role: worker
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: <windows_machine_set_name>
6 

        machine.openshift.io/os-id: Windows
7 

    spec:
      metadata:
        labels:
          node-role.kubernetes.io/worker: ""
8 

      providerSpec:
        value:
          apiVersion: azureproviderconfig.openshift.io/v1beta1
          credentialsSecret:
            name: azure-cloud-credentials
            namespace: openshift-machine-api
          image:
9 

            offer: WindowsServer
            publisher: MicrosoftWindowsServer
            resourceID: ""
            sku: 2019-Datacenter-with-Containers
            version: latest
          kind: AzureMachineProviderSpec
          location: <location>
10 

          managedIdentity: <infrastructure_id>-identity
11 

          networkResourceGroup: <infrastructure_id>-rg
12 

          osDisk:
            diskSizeGB: 128
            managedDisk:
              storageAccountType: Premium_LRS
            osType: Windows
          publicIP: false
          resourceGroup: <infrastructure_id>-rg
13 

          subnet: <infrastructure_id>-worker-subnet
          userDataSecret:
            name: windows-user-data
14 

            namespace: openshift-machine-api
          vmSize: Standard_D2s_v3
          vnet: <infrastructure_id>-vnet
15 

          zone: "<zone>"
16
Copy to Clipboard Toggle word wrap
1 3 5 11 12 13 15
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. You can obtain the infrastructure ID by running the following command: 
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
Copy to Clipboard Toggle word wrap
2 4 6
Specify the Windows machine set name. Windows machine names on Azure cannot be more than 15 characters long. Therefore, the machine set name cannot be more than 9 characters long, due to the way machine names are generated from it.
7
Configure the machine set as a Windows machine.
8
Configure the Windows node as a compute machine.
9
Specify a WindowsServer image offering that defines the 2019-Datacenter-with-Containers SKU.
10
Specify the Azure region, like centralus.
14
Created by the WMCO when it is configuring the first Windows machine. After that, the windows-user-data is available for all subsequent machine sets to consume.
16
Specify the zone within your region to place machines on. Be sure that your region supports the zone that you specify.

5.2.3. Creating a machine set
Copy link

In addition to the ones created by the installation program, you can create your own machine sets 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 machine set custom resource (CR) sample and is named <file_name>.yaml.

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

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

      $ oc get machinesets -n openshift-machine-api
      Copy to Clipboard Toggle word wrap

      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
      Copy to Clipboard Toggle word wrap

    2. Check values of a specific machine set: 

      $ oc get machineset <machineset_name> -n \
     openshift-machine-api -o yaml
      Copy to Clipboard Toggle word wrap

      Example output

      ...
template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: agl030519-vplxk
      1 
      
        machine.openshift.io/cluster-api-machine-role: worker
      2 
      
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a
      Copy to Clipboard Toggle word wrap

      1
      The cluster ID.
      2
      A default node label.

  2. Create the new MachineSet CR: 

    $ oc create -f <file_name>.yaml
    Copy to Clipboard Toggle word wrap

  3. View the list of machine sets: 

    $ oc get machineset -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

    Example output

    NAME                                      DESIRED   CURRENT   READY   AVAILABLE   AGE
agl030519-vplxk-windows-worker-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
    Copy to Clipboard Toggle word wrap

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

You can create a Windows MachineSet object to serve a specific purpose in your OpenShift Container Platform cluster on VMware vSphere. For example, you might create infrastructure Windows machine sets and related machines so that you can move supporting Windows workloads to the new Windows machines.

Prerequisites
  • You installed the Windows Machine Config Operator (WMCO) using Operator Lifecycle Manager (OLM).
  • You are using a supported Windows Server as the operating system image with the Docker-formatted container runtime add-on enabled.
Important

Currently, the Docker-formatted container runtime is used in Windows nodes. Kubernetes is deprecating Docker as a container runtime; you can reference the Kubernetes documentation for more information on Docker deprecation. Containerd will be the new supported container runtime for Windows nodes in a future release of Kubernetes.

5.3.1. Machine API overview
Copy link

The Machine API is a combination of primary resources that are based on the upstream Cluster API project and custom OpenShift Container Platform resources.

For OpenShift Container Platform 4.8 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.8 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:

Machines
A fundamental unit that describes the host for a node. A machine has a providerSpec specification, which describes the types of compute nodes that are offered for different cloud platforms. For example, a machine type for a worker node on Amazon Web Services (AWS) might define a specific machine type and required metadata.
Machine sets

MachineSet resources are groups of machines. Machine sets are to machines as replica sets are to pods. If you need more machines or must scale them down, you change the replicas field on the machine set to meet your compute need.

Warning

Control plane machines cannot be managed by machine sets.

The following custom resources add more capabilities to your cluster:

Machine autoscaler
The MachineAutoscaler resource automatically scales machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified machine set, and the machine autoscaler maintains that range of nodes. The MachineAutoscaler object takes effect after a ClusterAutoscaler object exists. Both ClusterAutoscaler and MachineAutoscaler resources are made available by the ClusterAutoscalerOperator object.
Cluster autoscaler
This resource is based on the upstream cluster autoscaler project. In the OpenShift Container Platform implementation, it is integrated with the Machine API by extending the machine set API. You can set cluster-wide scaling limits for resources such as cores, nodes, memory, GPU, and so on. You can set the priority so that the cluster prioritizes pods so that new nodes are not brought online for less important pods. You can also set the scaling policy so that you can scale up nodes but not scale them down.
Machine health check
The MachineHealthCheck resource detects when a machine is unhealthy, deletes it, and, on supported platforms, makes a new machine.

In OpenShift Container Platform version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OpenShift Container Platform version 4.1, this process is easier. Each machine set is scoped to a single zone, so the installation program sends out machine sets across availability zones on your behalf. And then because your compute is dynamic, and in the face of a zone failure, you always have a zone for when you must rebalance your machines. The autoscaler provides best-effort balancing over the life of a cluster.

You must prepare your vSphere environment for Windows container workloads by creating the vSphere Windows VM golden image and enabling communication with the internal API server for the WMCO.

Create a vSphere Windows virtual machine (VM) golden image.

Prerequisites

  • You have created a private/public key pair, which is used to configure key-based authentication in the OpenSSH server. The private key must also be configured in the Windows Machine Config Operator (WMCO) namespace. This is required to allow the WMCO to communicate with the Windows VM. See the "Configuring a secret for the Windows Machine Config Operator" section for more details.
Note

You must use Microsoft PowerShell commands in several cases when creating your Windows VM. PowerShell commands in this guide are distinguished by the PS C:\> prefix.

Procedure

  1. Create a new VM in the vSphere client using Windows Server 2022, OS Build 20348.681 or later.

    Important

    The virtual hardware version for your VM must meet the infrastructure requirements for OpenShift Container Platform. For more information, see the "VMware vSphere infrastructure requirements" section in the OpenShift Container Platform documentation. Also, you can refer to VMware’s documentation on virtual machine hardware versions.

  2. Install and configure VMware Tools version 11.0.6 or greater on the Windows VM. See the VMware Tools documentation for more information.

  3. After installing VMware Tools on the Windows VM, verify the following:

    1. The C:\ProgramData\VMware\VMware Tools\tools.conf file exists with the following entry: 

      exclude-nics=
      Copy to Clipboard Toggle word wrap

      If the tools.conf file does not exist, create it with the exclude-nics option uncommented and set as an empty value.

      This entry ensures the cloned vNIC generated on the Windows VM by the hybrid-overlay is not ignored.

    2. The Windows VM has a valid IP address in vCenter: 

      C:\> ipconfig
      Copy to Clipboard Toggle word wrap

    3. The VMTools Windows service is running: 

      PS C:\> Get-Service -Name VMTools | Select Status, StartType
      Copy to Clipboard Toggle word wrap
  4. Install and configure the OpenSSH Server on the Windows VM. See Microsoft’s documentation on installing OpenSSH for more details.

  5. Set up SSH access for an administrative user. See Microsoft’s documentation on the Administrative user to do this.

    Important

    The public key used in the instructions must correspond to the private key you create later in the WMCO namespace that holds your secret. See the "Configuring a secret for the Windows Machine Config Operator" section for more details.

  6. Install the docker container runtime on your Windows VM following the Microsoft documentation.

  7. You must create a new firewall rule in the Windows VM that allows incoming connections for container logs. Run the following PowerShell command to create the firewall rule on TCP port 10250: 

    PS C:\> New-NetFirewallRule -DisplayName "ContainerLogsPort" -LocalPort 10250 -Enabled True -Direction Inbound -Protocol TCP -Action Allow -EdgeTraversalPolicy Allow
    Copy to Clipboard Toggle word wrap
  8. Clone the Windows VM so it is a reusable image. Follow the VMware documentation on how to clone an existing virtual machine for more details.

  9. In the cloned Windows VM, run the Windows Sysprep tool: 

    C:\> C:\Windows\System32\Sysprep\sysprep.exe /generalize /oobe /shutdown /unattend:<path_to_unattend.xml>
    1
    Copy to Clipboard Toggle word wrap
    1
    Specify the path to your unattend.xml file.
    Note

    There is a limit on how many times you can run the sysprep command on a Windows image. Consult Microsoft’s documentation for more information.

    An example unattend.xml is provided, which maintains all the changes needed for the WMCO. You must modify this example; it cannot be used directly.

    Example 5.1. Example unattend.xml

    <?xml version="1.0" encoding="UTF-8"?>
<unattend xmlns="urn:schemas-microsoft-com:unattend">
   <settings pass="specialize">
      <component xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Microsoft-Windows-International-Core" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
         <InputLocale>0409:00000409</InputLocale>
         <SystemLocale>en-US</SystemLocale>
         <UILanguage>en-US</UILanguage>
         <UILanguageFallback>en-US</UILanguageFallback>
         <UserLocale>en-US</UserLocale>
      </component>
      <component xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Microsoft-Windows-Security-SPP-UX" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
         <SkipAutoActivation>true</SkipAutoActivation>
      </component>
      <component xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Microsoft-Windows-SQMApi" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
         <CEIPEnabled>0</CEIPEnabled>
      </component>
      <component xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Microsoft-Windows-Shell-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
         <ComputerName>winhost</ComputerName>
    1 
    
      </component>
   </settings>
   <settings pass="oobeSystem">
      <component xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Microsoft-Windows-Shell-Setup" processorArchitecture="amd64" publicKeyToken="31bf3856ad364e35" language="neutral" versionScope="nonSxS">
         <AutoLogon>
            <Enabled>false</Enabled>
    2 
    
         </AutoLogon>
         <OOBE>
            <HideEULAPage>true</HideEULAPage>
            <HideLocalAccountScreen>true</HideLocalAccountScreen>
            <HideOEMRegistrationScreen>true</HideOEMRegistrationScreen>
            <HideOnlineAccountScreens>true</HideOnlineAccountScreens>
            <HideWirelessSetupInOOBE>true</HideWirelessSetupInOOBE>
            <NetworkLocation>Work</NetworkLocation>
            <ProtectYourPC>1</ProtectYourPC>
            <SkipMachineOOBE>true</SkipMachineOOBE>
            <SkipUserOOBE>true</SkipUserOOBE>
         </OOBE>
         <RegisteredOrganization>Organization</RegisteredOrganization>
         <RegisteredOwner>Owner</RegisteredOwner>
         <DisableAutoDaylightTimeSet>false</DisableAutoDaylightTimeSet>
         <TimeZone>Eastern Standard Time</TimeZone>
         <UserAccounts>
            <AdministratorPassword>
               <Value>MyPassword</Value>
    3 
    
               <PlainText>true</PlainText>
            </AdministratorPassword>
         </UserAccounts>
      </component>
   </settings>
</unattend>
    Copy to Clipboard Toggle word wrap
    1
    Specify the ComputerName, which must follow the Kubernetes' names specification. These specifications also apply to Guest OS customization performed on the resulting template while creating new VMs.
    2
    Disable the automatic logon to avoid the security issue of leaving an open terminal with Administrator privileges at boot. This is the default value and must not be changed.
    3
    Replace the MyPassword placeholder with the password for the Administrator account. This prevents the built-in Administrator account from having a blank password by default. Follow Microsoft’s best practices for choosing a password.

    After the Sysprep tool has completed, the Windows VM will power off. You must not use or power on this VM anymore.

  10. Convert the Windows VM to a template in vCenter.

The Windows Machine Config Operator (WMCO) downloads the Ignition config files from the internal API server endpoint. You must enable communication with the internal API server so that your Windows virtual machine (VM) can download the Ignition config files, and the kubelet on the configured VM can only communicate with the internal API server.

Prerequisites

  • You have installed a cluster on vSphere.

Procedure

  • Add a new DNS entry for api-int.<cluster_name>.<base_domain> that points to the external API server URL api.<cluster_name>.<base_domain>. This can be a CNAME or an additional A record.
Note

The external API endpoint was already created as part of the initial cluster installation on vSphere.

This sample YAML defines a Windows MachineSet object running on VMware vSphere that the Windows Machine Config Operator (WMCO) can react upon. 

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id>
1 

  name: <windows_machine_set_name>
2 

  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id>
3 

      machine.openshift.io/cluster-api-machineset: <windows_machine_set_name>
4 

  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
5 

        machine.openshift.io/cluster-api-machine-role: worker
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: <windows_machine_set_name>
6 

        machine.openshift.io/os-id: Windows
7 

    spec:
      metadata:
        labels:
          node-role.kubernetes.io/worker: ""
8 

      providerSpec:
        value:
          apiVersion: vsphereprovider.openshift.io/v1beta1
          credentialsSecret:
            name: vsphere-cloud-credentials
          diskGiB: 128
9 

          kind: VSphereMachineProviderSpec
          memoryMiB: 16384
          network:
            devices:
            - networkName: "<vm_network_name>"
10 

          numCPUs: 4
          numCoresPerSocket: 1
          snapshot: ""
          template: <windows_vm_template_name>
11 

          userDataSecret:
            name: windows-user-data
12 

          workspace:
             datacenter: <vcenter_datacenter_name>
13 

             datastore: <vcenter_datastore_name>
14 

             folder: <vcenter_vm_folder_path>
15 

             resourcePool: <vsphere_resource_pool>
16 

             server: <vcenter_server_ip>
17
Copy to Clipboard Toggle word wrap
1 3 5
Specify the infrastructure ID that is based on the cluster ID that you set when you provisioned the cluster. You can obtain the infrastructure ID by running the following command: 
$ oc get -o jsonpath='{.status.infrastructureName}{"\n"}' infrastructure cluster
Copy to Clipboard Toggle word wrap
2 4 6
Specify the Windows machine set name. The machine set name cannot be more than 9 characters long, due to the way machine names are generated in vSphere.
7
Configure the machine set as a Windows machine.
8
Configure the Windows node as a compute machine.
9
Specify the size of the vSphere Virtual Machine Disk (VMDK).
Note

This parameter does not set the size of the Windows partition. You can resize the Windows partition by using the unattend.xml file or by creating the vSphere Windows virtual machine (VM) golden image with the required disk size.

10
Specify the vSphere VM network to deploy the machine set to. This VM network must be where other Linux compute machines reside in the cluster.
11
Specify the full path of the Windows vSphere VM template to use, such as golden-images/windows-server-template. The name must be unique.
Important

Do not specify the original VM template. The VM template must remain off and must be cloned for new Windows machines. Starting the VM template configures the VM template as a VM on the platform, which prevents it from being used as a template that machine sets can apply configurations to.

12
The windows-user-data is created by the WMCO when the first Windows machine is configured. After that, the windows-user-data is available for all subsequent machine sets to consume.
13
Specify the vCenter Datacenter to deploy the machine set on.
14
Specify the vCenter Datastore to deploy the machine set on.
15
Specify the path to the vSphere VM folder in vCenter, such as /dc1/vm/user-inst-5ddjd.
16
Optional: Specify the vSphere resource pool for your Windows VMs.
17
Specify the vCenter server IP or fully qualified domain name.

5.3.4. Creating a machine set
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In addition to the ones created by the installation program, you can create your own machine sets 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 machine set custom resource (CR) sample and is named <file_name>.yaml.

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

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

      $ oc get machinesets -n openshift-machine-api
      Copy to Clipboard Toggle word wrap

      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
      Copy to Clipboard Toggle word wrap

    2. Check values of a specific machine set: 

      $ oc get machineset <machineset_name> -n \
     openshift-machine-api -o yaml
      Copy to Clipboard Toggle word wrap

      Example output

      ...
template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: agl030519-vplxk
      1 
      
        machine.openshift.io/cluster-api-machine-role: worker
      2 
      
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: agl030519-vplxk-worker-us-east-1a
      Copy to Clipboard Toggle word wrap

      1
      The cluster ID.
      2
      A default node label.

  2. Create the new MachineSet CR: 

    $ oc create -f <file_name>.yaml
    Copy to Clipboard Toggle word wrap

  3. View the list of machine sets: 

    $ oc get machineset -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

    Example output

    NAME                                      DESIRED   CURRENT   READY   AVAILABLE   AGE
agl030519-vplxk-windows-worker-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
    Copy to Clipboard Toggle word wrap

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

Chapter 6. Scheduling Windows container workloads
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You can schedule Windows workloads to Windows compute nodes.

Note

The WMCO is not supported in clusters that use a cluster-wide proxy because the WMCO is not able to route traffic through the proxy connection for the workloads.

Prerequisites

  • You installed the Windows Machine Config Operator (WMCO) using Operator Lifecycle Manager (OLM).
  • You are using a Windows container as the OS image with the Docker-formatted container runtime add-on enabled.
  • You have created a Windows machine set.
Important

Currently, the Docker-formatted container runtime is used in Windows nodes. Kubernetes is deprecating Docker as a container runtime; you can reference the Kubernetes documentation for more information in Docker deprecation. Containerd will be the new supported container runtime for Windows nodes in a future release of Kubernetes.

6.1. Windows pod placement
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Before deploying your Windows workloads to the cluster, you must configure your Windows node scheduling so pods are assigned correctly. Since you have a machine hosting your Windows node, it is managed the same as a Linux-based node. Likewise, scheduling a Windows pod to the appropriate Windows node is completed similarly, using mechanisms like taints, tolerations, and node selectors.

With multiple operating systems, and the ability to run multiple Windows OS variants in the same cluster, you must map your Windows pods to a base Windows OS variant by using a RuntimeClass object. For example, if you have multiple Windows nodes running on different Windows Server container versions, the cluster could schedule your Windows pods to an incompatible Windows OS variant. You must have RuntimeClass objects configured for each Windows OS variant on your cluster. Using a RuntimeClass object is also recommended if you have only one Windows OS variant available in your cluster.

For more information, see Microsoft’s documentation on Host and container version compatibility.

Important

The container base image must be the same Windows OS version and build number that is running on the node where the conainer is to be scheduled.

Also, if you upgrade the Windows nodes from one version to another, for example going from 20H2 to 2022, you must upgrade your container base image to match the new version. For more information, see Windows container version compatibility.

Additional resources

Using a RuntimeClass object simplifies the use of scheduling mechanisms like taints and tolerations; you deploy a runtime class that encapsulates your taints and tolerations and then apply it to your pods to schedule them to the appropriate node. Creating a runtime class is also necessary in clusters that support multiple operating system variants.

Procedure

  1. Create a RuntimeClass object YAML file. For example, runtime-class.yaml: 

    apiVersion: node.k8s.io/v1beta1
kind: RuntimeClass
metadata:
  name: <runtime_class_name>
    1 
    
handler: 'docker'
scheduling:
  nodeSelector:
    2 
    
    kubernetes.io/os: 'windows'
    kubernetes.io/arch: 'amd64'
    node.kubernetes.io/windows-build: '10.0.17763'
  tolerations:
    3 
    
  - effect: NoSchedule
    key: os
    operator: Equal
    value: "Windows"
    Copy to Clipboard Toggle word wrap
    1
    Specify the RuntimeClass object name, which is defined in the pods you want to be managed by this runtime class.
    2
    Specify labels that must be present on nodes that support this runtime class. Pods using this runtime class can only be scheduled to a node matched by this selector. The node selector of the runtime class is merged with the existing node selector of the pod. Any conflicts prevent the pod from being scheduled to the node.
    3
    Specify tolerations to append to pods, excluding duplicates, running with this runtime class during admission. This combines the set of nodes tolerated by the pod and the runtime class.

  2. Create the RuntimeClass object: 

    $ oc create -f <file-name>.yaml
    Copy to Clipboard Toggle word wrap

    For example: 

    $ oc create -f runtime-class.yaml
    Copy to Clipboard Toggle word wrap

  3. Apply the RuntimeClass object to your pod to ensure it is scheduled to the appropriate operating system variant: 

    apiVersion: v1
kind: Pod
metadata:
  name: my-windows-pod
spec:
  runtimeClassName: <runtime_class_name>
    1 
    
...
    Copy to Clipboard Toggle word wrap
    1
    Specify the runtime class to manage the scheduling of your pod.

6.3. Sample Windows container workload deployment
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You can deploy Windows container workloads to your cluster once you have a Windows compute node available.

Note

This sample deployment is provided for reference only.

Example Service object

apiVersion: v1
kind: Service
metadata:
  name: win-webserver
  labels:
    app: win-webserver
spec:
  ports:
    # the port that this service should serve on
  - port: 80
    targetPort: 80
  selector:
    app: win-webserver
  type: LoadBalancer
Copy to Clipboard Toggle word wrap

Example Deployment object

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: win-webserver
  name: win-webserver
spec:
  selector:
    matchLabels:
      app: win-webserver
  replicas: 1
  template:
    metadata:
      labels:
        app: win-webserver
      name: win-webserver
    spec:
      tolerations:
      - key: "os"
        value: "Windows"
        Effect: "NoSchedule"
      containers:
      - name: windowswebserver
        image: mcr.microsoft.com/windows/servercore:ltsc2019
        imagePullPolicy: IfNotPresent
        command:
        - powershell.exe
        - -command
        - $listener = New-Object System.Net.HttpListener; $listener.Prefixes.Add('http://*:80/'); $listener.Start();Write-Host('Listening at http://*:80/'); while ($listener.IsListening) { $context = $listener.GetContext(); $response = $context.Response; $content='<html><body><H1>Red Hat OpenShift + Windows Container Workloads</H1></body></html>'; $buffer = [System.Text.Encoding]::UTF8.GetBytes($content); $response.ContentLength64 = $buffer.Length; $response.OutputStream.Write($buffer, 0, $buffer.Length); $response.Close(); };
        securityContext:
          runAsNonRoot: false
          windowsOptions:
            runAsUserName: "ContainerAdministrator"
      nodeSelector:
        kubernetes.io/os: windows
Copy to Clipboard Toggle word wrap

Note

When using the mcr.microsoft.com/powershell:<tag> container image, you must define the command as pwsh.exe. If you are using the mcr.microsoft.com/windows/servercore:<tag> container image, you must define the command as powershell.exe. For more information, see Microsoft’s documentation.

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

This guidance is relevant to fully automated, installer-provisioned infrastructure installations. Customized, user-provisioned infrastructure installations do not have 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 machine sets that are in the cluster: 

    $ oc get machinesets -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

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

  2. View the machines that are in the cluster: 

    $ oc get machine -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

  3. Set the annotation on the machine that you want to delete: 

    $ oc annotate machine/<machine_name> -n openshift-machine-api machine.openshift.io/cluster-api-delete-machine="true"
    Copy to Clipboard Toggle word wrap

  4. Cordon and drain the node that you want to delete: 

    $ oc adm cordon <node_name>
$ oc adm drain <node_name>
    Copy to Clipboard Toggle word wrap

  5. Scale the machine set: 

    $ oc scale --replicas=2 machineset <machineset> -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

    Or: 

    $ oc edit machineset <machineset> -n openshift-machine-api
    Copy to Clipboard Toggle word wrap
    Tip

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

    apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  name: <machineset>
  namespace: openshift-machine-api
spec:
  replicas: 2
    Copy to Clipboard Toggle word wrap

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

Verification

  • Verify the deletion of the intended machine: 

    $ oc get machines
    Copy to Clipboard Toggle word wrap

Chapter 7. Windows node upgrades
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You can ensure your Windows nodes have the latest updates by upgrading the Windows Machine Config Operator (WMCO).

7.1. Windows Machine Config Operator upgrades
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When a new version of the Windows Machine Config Operator (WMCO) is released that is compatible with the current cluster version, the Operator is upgraded based on the upgrade channel and subscription approval strategy it was installed with when using the Operator Lifecycle Manager (OLM). The WMCO upgrade results in the Kubernetes components in the Windows machine being upgraded.

Note

If you are upgrading to a new version of the WMCO and want to use cluster monitoring, you must have the openshift.io/cluster-monitoring=true label present in the WMCO namespace. If you add the label to a pre-existing WMCO namespace, and there are already Windows nodes configured, restart the WMCO pod to allow monitoring graphs to display.

For a non-disruptive upgrade, the WMCO terminates the Windows machines configured by the previous version of the WMCO and recreates them using the current version. This is done by deleting the Machine object, which results in the drain and deletion of the Windows node. To facilitate an upgrade, the WMCO adds a version annotation to all the configured nodes. During an upgrade, a mismatch in version annotation results in the deletion and recreation of a Windows machine. To have minimal service disruptions during an upgrade, the WMCO only updates one Windows machine at a time.

Important

The WMCO is only responsible for updating Kubernetes components, not for Windows operating system updates. You provide the Windows image when creating the VMs; therefore, you are responsible for providing an updated image. You can provide an updated Windows image by changing the image configuration in the MachineSet spec.

For more information on Operator upgrades using the Operator Lifecycle Manager (OLM), see Updating installed Operators.

Bring-Your-Own-Host (BYOH) allows for users to repurpose Windows Server VMs and bring them to OpenShift Container Platform. BYOH Windows instances benefit users looking to mitigate major disruptions in the event that a Windows server goes offline.

8.1. Configuring a BYOH Windows instance
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Creating a BYOH Windows instance requires creating a config map in the Windows Machine Config Operator (WMCO) namespace.

Prerequisites

Any Windows instances that are to be attached to the cluster as a node must fulfill the following requirements:

  • The Docker container runtime must be installed on the instance.
  • The instance must be on the same network as the Linux worker nodes in the cluster.
  • Port 22 must be open and running an SSH server.
  • The default shell for the SSH server must be the Windows Command shell, or cmd.exe.
  • Port 10250 must be open for log collection.
  • An administrator user is present with the private key used in the secret set as an authorized SSH key.
  • If you are creating a BYOH Windows instance for an installer-provisioned infrastructure (IPI) AWS cluster, you must add a tag to the AWS instance that matches the spec.template.spec.value.tag value in the machine set for your worker nodes. For example, kubernetes.io/cluster/<cluster_id>: owned or kubernetes.io/cluster/<cluster_id>: shared.
  • If you are creating a BYOH Windows instance on vSphere, communication with the internal API server must be enabled.

  • The hostname of the instance must follow the RFC 1123 DNS label requirements, which include the following standards:

    • Contains only lowercase alphanumeric characters or '-'.
    • Starts with an alphanumeric character.
    • Ends with an alphanumeric character.

Procedure

  1. Create a ConfigMap named windows-instances in the WMCO namespace that describes the Windows instances to be added.

    Note

    Format each entry in the config map’s data section by using the address as the key while formatting the value as username=<username>.

    Example config map

    kind: ConfigMap
apiVersion: v1
metadata:
  name: windows-instances
  namespace: openshift-windows-machine-config-operator
data:
  10.1.42.1: |-
    1 
    
    username=Administrator
    2 
    
  instance.example.com: |-
    username=core
    Copy to Clipboard Toggle word wrap

    1
    The address that the WMCO uses to reach the instance over SSH, either a DNS name or an IPv4 address. A DNS PTR record must exist for this address. It is recommended that you use a DNS name with your BYOH instance if your organization uses DHCP to assign IP addresses. If not, you need to update the windows-instances ConfigMap whenever the instance is assigned a new IP address.
    2
    The name of the administrator user created in the prerequisites.

8.2. Removing BYOH Windows instances
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You can remove BYOH instances attached to the cluster by deleting the instance’s entry in the config map. Deleting an instance reverts that instance back to its state prior to adding to the cluster. Any logs and container runtime artifacts are not added to these instances.

For an instance to be cleanly removed, it must be accessible with the current private key provided to WMCO. For example, to remove the 10.1.42.1 instance from the previous example, the config map would be changed to the following: 

kind: ConfigMap
apiVersion: v1
metadata:
  name: windows-instances
  namespace: openshift-windows-machine-config-operator
data:
  instance.example.com: |-
    username=core
Copy to Clipboard Toggle word wrap

Deleting windows-instances is viewed as a request to deconstruct all Windows instances added as nodes.

Chapter 9. Removing Windows nodes
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You can remove a Windows node by deleting its host Windows machine.

9.1. Deleting a specific machine
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You can delete a specific machine.

Note

You cannot delete a control plane machine.

Prerequisites

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

Procedure

  1. View the machines that are in the cluster and identify the one to delete: 

    $ oc get machine -n openshift-machine-api
    Copy to Clipboard Toggle word wrap

    The command output contains a list of machines in the <clusterid>-worker-<cloud_region> format.

  2. Delete the machine: 

    $ oc delete machine <machine> -n openshift-machine-api
    Copy to Clipboard Toggle word wrap
    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 in preventing the machine from being deleted. You can skip draining the node by annotating "machine.openshift.io/exclude-node-draining" in a specific machine. If the machine being deleted belongs to a machine set, a new machine is immediately created to satisfy the specified number of replicas.

Chapter 10. Disabling Windows container workloads
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You can disable the capability to run Windows container workloads by uninstalling the Windows Machine Config Operator (WMCO) and deleting the namespace that was added by default when you installed the WMCO.

You can uninstall the Windows Machine Config Operator (WMCO) from your cluster.

Prerequisites

  • Delete the Windows Machine objects hosting your Windows workloads.

Procedure

  1. From the Operators → OperatorHub page, use the Filter by keyword box to search for Red Hat Windows Machine Config Operator.
  2. Click the Red Hat Windows Machine Config Operator tile. The Operator tile indicates it is installed.
  3. In the Windows Machine Config Operator descriptor page, click Uninstall.

You can delete the namespace that was generated for the Windows Machine Config Operator (WMCO) by default.

Prerequisites

  • The WMCO is removed from your cluster.

Procedure

  1. Remove all Windows workloads that were created in the openshift-windows-machine-config-operator namespace: 

    $ oc delete --all pods --namespace=openshift-windows-machine-config-operator
    Copy to Clipboard Toggle word wrap

  2. Verify that all pods in the openshift-windows-machine-config-operator namespace are deleted or are reporting a terminating state: 

    $ oc get pods --namespace openshift-windows-machine-config-operator
    Copy to Clipboard Toggle word wrap

  3. Delete the openshift-windows-machine-config-operator namespace: 

    $ oc delete namespace openshift-windows-machine-config-operator
    Copy to Clipboard Toggle word wrap

Additional resources

Legal Notice
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Copyright © 2025 Red Hat

OpenShift documentation is licensed under the Apache License 2.0 (https://www.apache.org/licenses/LICENSE-2.0).

Modified versions must remove all Red Hat trademarks.

Portions adapted from https://github.com/kubernetes-incubator/service-catalog/ with modifications by Red Hat.

Red Hat, Red Hat Enterprise Linux, the Red Hat logo, the Shadowman logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries.

Linux® is the registered trademark of Linus Torvalds in the United States and other countries.

Java® is a registered trademark of Oracle and/or its affiliates.

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All other trademarks are the property of their respective owners.

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