You can create a Windows MachineSet object to serve a specific purpose in your OKD 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.


  • 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

    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.

Machine API overview

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

For OKD 4.6 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OKD 4.6 offers an elastic, dynamic provisioning method on top of public or private cloud infrastructure.

The two primary resources are:


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.

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 OKD 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 OKD version 3.11, you could not roll out a multi-zone architecture easily because the cluster did not manage machine provisioning. Beginning with OKD 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.

Sample YAML for a Windows MachineSet object on AWS

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
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
  name: <infrastructure_id>-windows-worker-<zone> (2)
  namespace: openshift-machine-api
  replicas: 1
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
      machine.openshift.io/cluster-api-machineset: <infrastructure_id>-windows-worker-<zone> (2)
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
        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> (2)
        machine.openshift.io/os-id: Windows (3)
          node-role.kubernetes.io/worker: "" (4)
            id: <windows_container_ami> (5)
          apiVersion: awsproviderconfig.openshift.io/v1beta1
            - ebs:
                iops: 0
                volumeSize: 120
                volumeType: gp2
            name: aws-cloud-credentials
          deviceIndex: 0
            id: <infrastructure_id>-worker-profile (1)
          instanceType: m5a.large
          kind: AWSMachineProviderConfig
            availabilityZone: <zone> (6)
            region: <region> (7)
            - filters:
                - name: tag:Name
                    - <infrastructure_id>-worker-sg (1)
              - name: tag:Name
                  - <infrastructure_id>-private-<zone> (1)
            - name: kubernetes.io/cluster/<infrastructure_id> (1)
              value: owned
            name: windows-user-data (8)
            namespace: openshift-machine-api
1 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
2 Specify the infrastructure ID, worker label, and zone.
3 Configure the machine set as a Windows machine.
4 Configure the Windows node as a compute machine.
5 Specify the AMI ID of a Windows image with a container runtime installed. You must use Windows Server 2019 with a version 10.0.17763.1457 or earlier.
6 Specify the AWS zone, like us-east-1a.
7 Specify the AWS region, like us-east-1.
8 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.

Creating a machine set

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.

  • Deploy an OKD cluster.

  • Install the OpenShift CLI (oc).

  • Log in to oc as a user with cluster-admin permission.

  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
      Example output
      NAME                                DESIRED   CURRENT   READY   AVAILABLE   AGE
      agl030519-vplxk-worker-us-east-1a   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1b   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1c   1         1         1       1           55m
      agl030519-vplxk-worker-us-east-1d   0         0                             55m
      agl030519-vplxk-worker-us-east-1e   0         0                             55m
      agl030519-vplxk-worker-us-east-1f   0         0                             55m
    2. Check values of a specific machine set:

      $ oc get machineset <machineset_name> -n \
           openshift-machine-api -o yaml
      Example output
              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
      1 The cluster ID.
      2 A default node label.
  2. Create the new MachineSet CR:

    $ oc create -f <file_name>.yaml
  3. View the list of machine sets:

    $ oc get machineset -n openshift-machine-api
    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

    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.

Additional resources

  • For more information on managing machine sets, see the Machine management section.