Creating a cluster with multi-architecture compute machines on GCP - Configuring multi-architecture compute machines on an OpenShift cluster | Postinstallation configuration

Verifying cluster compatibility
Adding a multi-architecture compute machine set to your GCP cluster

To create a Google Cloud Platform (GCP) cluster with multi-architecture compute machines, you must first create a single-architecture GCP installer-provisioned cluster with the multi-architecture installer binary. For more information on AWS installations, see Installing a cluster on GCP with customizations.

You can also migrate your current cluster with single-architecture compute machines to a cluster with multi-architecture compute machines. For more information, see Migrating to a cluster with multi-architecture compute machines.

After creating a multi-architecture cluster, you can add nodes with different architectures to the cluster.

Secure booting is currently not supported on 64-bit ARM machines for GCP

Verifying cluster compatibility

Before you can start adding compute nodes of different architectures to your cluster, you must verify that your cluster is multi-architecture compatible.

Prerequisites

You installed the OpenShift cli (oc).

Procedure

Log in to the OpenShift cli (oc).
You can check that your cluster uses the architecture payload by running the following command:
```
$ oc adm release info -o jsonpath="{ .metadata.metadata}"
```

Verification

If you see the following output, your cluster is using the multi-architecture payload:
```
{
 "release.openshift.io/architecture": "multi",
 "url": "https://access.redhat.com/errata/<errata_version>"
}
```
You can then begin adding multi-arch compute nodes to your cluster.
If you see the following output, your cluster is not using the multi-architecture payload:
```
{
 "url": "https://access.redhat.com/errata/<errata_version>"
}
```
To migrate your cluster so the cluster supports multi-architecture compute machines, follow the procedure in Migrating to a cluster with multi-architecture compute machines.

Adding a multi-architecture compute machine set to your GCP cluster

After creating a multi-architecture cluster, you can add nodes with different architectures.

You can add multi-architecture compute machines to a multi-architecture cluster in the following ways:

Adding 64-bit x86 compute machines to a cluster that uses 64-bit ARM control plane machines and already includes 64-bit ARM compute machines. In this case, 64-bit x86 is considered the secondary architecture.
Adding 64-bit ARM compute machines to a cluster that uses 64-bit x86 control plane machines and already includes 64-bit x86 compute machines. In this case, 64-bit ARM is considered the secondary architecture.

Before adding a secondary architecture node to your cluster, it is recommended to install the Multiarch Tuning Operator, and deploy a ClusterPodPlacementConfig custom resource. For more information, see "Managing workloads on multi-architecture clusters by using the Multiarch Tuning Operator".

Prerequisites

You installed the OpenShift cli (oc).
You used the installation program to create a 64-bit x86 or 64-bit ARM single-architecture GCP cluster with the multi-architecture installer binary.

Procedure

Create a YAML file, and add the configuration to create a compute machine set to control the 64-bit ARM or 64-bit x86 compute nodes in your cluster.

Example MachineSet object for a GCP 64-bit ARM or 64-bit x86 compute node

apiVersion: machine.openshift.io/v1beta1
kind: MachineSet
metadata:
  labels:
    machine.openshift.io/cluster-api-cluster: <infrastructure_id> (1)
  name: <infrastructure_id>-w-a
  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>-w-a
  template:
    metadata:
      creationTimestamp: null
      labels:
        machine.openshift.io/cluster-api-cluster: <infrastructure_id>
        machine.openshift.io/cluster-api-machine-role: <role> (2)
        machine.openshift.io/cluster-api-machine-type: <role>
        machine.openshift.io/cluster-api-machineset: <infrastructure_id>-w-a
    spec:
      metadata:
        labels:
          node-role.kubernetes.io/<role>: ""
      providerSpec:
        value:
          apiVersion: gcpprovider.openshift.io/v1beta1
          canIPForward: false
          credentialsSecret:
            name: gcp-cloud-credentials
          deletionProtection: false
          disks:
          - autoDelete: true
            boot: true
            image: <path_to_image> (3)
            labels: null
            sizeGb: 128
            type: pd-ssd
          gcpMetadata: (4)
          - key: <custom_metadata_key>
            value: <custom_metadata_value>
          kind: GCPMachineProviderSpec
          machineType: n1-standard-4 (5)
          metadata:
            creationTimestamp: null
          networkInterfaces:
          - network: <infrastructure_id>-network
            subnetwork: <infrastructure_id>-worker-subnet
          projectID: <project_name> (6)
          region: us-central1 (7)
          serviceAccounts:
          - email: <infrastructure_id>-w@<project_name>.iam.gserviceaccount.com
            scopes:
            - https://www.googleapis.com/auth/cloud-platform
          tags:
            - <infrastructure_id>-worker
          userDataSecret:
            name: worker-user-data
          zone: us-central1-a

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 role node label to add.
3	Specify the path to the image that is used in current compute machine sets. You need the project and image name for your path to image. To access the project and image name, run the following command: `$ oc get configmap/coreos-bootimages \ -n openshift-machine-config-operator \ -o jsonpath='{.data.stream}' \| jq \ -r '.architectures.aarch64.images.gcp'` Example output `"gcp": { "release": "415.92.202309142014-0", "project": "rhcos-cloud", "name": "rhcos-415-92-202309142014-0-gcp-aarch64" }` Use the `project` and `name` parameters from the output to create the path to image field in your machine set. The path to the image should follow the following format: `$ projects/<project>/global/images/<image_name>`
4	Optional: Specify custom metadata in the form of a `key:value` pair. For example use cases, see the GCP documentation for setting custom metadata.
5	Specify a machine type that aligns with the CPU architecture of the chosen OS image. For more information, see "Tested instance types for GCP on 64-bit ARM infrastructures".
6	Specify the name of the GCP project that you use for your cluster.
7	Specify the region. For example, `us-central1`. Ensure that the zone you select has machines with the required architecture.

Create the compute machine set by running the following command:
```
$ oc create -f <file_name> (1)
```
1 Replace <file_name> with the name of the YAML file with compute machine set configuration. For example: gcp-arm64-machine-set-0.yaml, or gcp-amd64-machine-set-0.yaml.

Verification

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

$ oc get machineset -n openshift-machine-api

The output must include the machine set that you created.

Example output

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

You can check if the nodes are ready and schedulable by running the following command:
```
$ oc get nodes
```

Additional resources