Creating a Windows machine set on Azure

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.

Machine API overview

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 4.19 clusters, the Machine API performs all node host provisioning management actions after the cluster installation finishes. Because of this system, OpenShift Container Platform 4.19 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 compute node might define a specific machine type and required metadata.
Machine sets: MachineSet resources are groups of compute machines. Compute machine sets are to compute machines as replica sets are to pods. If you need more compute machines or must scale them down, you change the replicas field on the MachineSet resource to meet your compute need.

Warning

Control plane machines cannot be managed by compute machine sets.

Control plane machine sets provide management capabilities for supported control plane machines that are similar to what compute machine sets provide for compute machines.

For more information, see “Managing control plane machines".

The following custom resources add more capabilities to your cluster:

Machine autoscaler

The MachineAutoscaler resource automatically scales compute machines in a cloud. You can set the minimum and maximum scaling boundaries for nodes in a specified compute 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 compute machine set API. You can use the cluster autoscaler to manage your cluster in the following ways:

Set cluster-wide scaling limits for resources such as cores, nodes, memory, and GPU
Set the priority so that the cluster prioritizes pods and new nodes are not brought online for less important pods
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 compute machine set is scoped to a single zone, so the installation program sends out compute 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. In global Azure regions that do not have multiple availability zones, you can use availability sets to ensure high availability. The autoscaler provides best-effort balancing over the life of a cluster.

Sample YAML for a Windows MachineSet object on Azure

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> 
  name: <windows_machine_set_name> 
  namespace: openshift-machine-api
spec:
  replicas: 1
  selector:
    matchLabels:
      machine.openshift.io/cluster-api-cluster: <infrastructure_id> 
      machine.openshift.io/cluster-api-machineset: <windows_machine_set_name> 
  template:
    metadata:
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id> 
        machine.openshift.io/cluster-api-machine-role: worker
        machine.openshift.io/cluster-api-machine-type: worker
        machine.openshift.io/cluster-api-machineset: <windows_machine_set_name> 
        machine.openshift.io/os-id: Windows 
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/worker: "" 
      providerSpec:
        value:
          apiVersion: azureproviderconfig.openshift.io/v1beta1
          credentialsSecret:
            name: azure-cloud-credentials
            namespace: openshift-machine-api
          image: 
            offer: WindowsServer
            publisher: MicrosoftWindowsServer
            resourceID: ""
            sku: 2019-Datacenter-with-Containers
            version: latest
          kind: AzureMachineProviderSpec
          location: <location> 
          networkResourceGroup: <infrastructure_id>-rg 
          osDisk:
            diskSizeGB: 128
            managedDisk:
              storageAccountType: Premium_LRS
            osType: Windows
          publicIP: false
          resourceGroup: <infrastructure_id>-rg 
          subnet: <infrastructure_id>-worker-subnet
          userDataSecret:
            name: windows-user-data 
            namespace: openshift-machine-api
          vmSize: Standard_D2s_v3
          vnet: <infrastructure_id>-vnet 
          zone: "<zone>"

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
```
Specify the Windows compute machine set name. Windows machine names on Azure cannot be more than 15 characters long. Therefore, the compute machine set name cannot be more than 9 characters long, due to the way machine names are generated from it.
Configure the compute machine set as a Windows machine.
Configure the Windows node as a compute machine.
Specify a WindowsServer image offering that defines the 2019-Datacenter-with-Containers SKU.
Specify the Azure region, like centralus.
Created by the WMCO when it is configuring the first Windows machine. After that, the windows-user-data is available for all subsequent compute machine sets to consume.
Specify the zone within your region to place machines on. Be sure that your region supports the zone that you specify.

Creating a compute machine set

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

Prerequisites

Deploy an OpenShift Container Platform cluster.
Install the OpenShift CLI (oc).
Log in to oc as a user with cluster-admin permission.
In disconnected environments, the image specified in the MachineSet custom resource (CR) must have the OpenSSH server v0.0.1.0 installed.

Procedure

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

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

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

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

$ oc get machinesets -n openshift-machine-api

Example output

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

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

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

Example output

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

The cluster infrastructure ID.
A default node label.
Note

For clusters that have user-provisioned infrastructure, a compute machine set can only create worker and infra type machines.
The values in the <providerSpec> section of the compute machine set CR are platform-specific. For more information about <providerSpec> parameters in the CR, see the sample compute machine set CR configuration for your provider.

Create a MachineSet CR by running the following command:
```
$ oc create -f <file_name>.yaml
```

Verification

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

$ oc get machineset -n openshift-machine-api

Example output

NAME                                       DESIRED   CURRENT   READY   AVAILABLE   AGE
agl030519-vplxk-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 compute machine set is available, the DESIRED and CURRENT values match. If the compute machine set is not available, wait a few minutes and run the command again.

Additional resources

Overview of machine management