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As an administrator, you can use feature gates to enable features that are not part of the default set of features.

Understanding feature gates

You can use the FeatureGate custom resource (CR) to enable specific feature sets in your cluster. A feature set is a collection of OpenShift Container Platform features that are not enabled by default.

You can activate the following feature set by using the FeatureGate CR:

  • TechPreviewNoUpgrade. This feature set is a subset of the current Technology Preview features. This feature set allows you to enable these tech preview features on test clusters, where you can fully test them, while leaving the features disabled on production clusters. Enabling this feature set cannot be undone and prevents minor version updates. This feature set is not recommended on production clusters.

    The following Technology Preview features are enabled by this feature set:

    • Microsoft Azure File CSI Driver Operator. Enables the provisioning of persistent volumes (PVs) by using the Container Storage Interface (CSI) driver for Microsoft Azure File Storage.

    • CSI automatic migration. Enables automatic migration for supported in-tree volume plug-ins to their equivalent Container Storage Interface (CSI) drivers. Supported for:

      • Amazon Web Services (AWS) Elastic Block Storage (EBS)

      • OpenStack Cinder

      • Azure Disk

      • Azure File

      • Google Cloud Platform Persistent Disk (CSI)

      • VMware vSphere

    • Cluster Cloud Controller Manager Operator. Enables the Cluster Cloud Controller Manager Operator rather than the in-tree cloud controller. Available as a Technology Preview for:

      • Alibaba Cloud

      • Amazon Web Services (AWS)

      • Google Cloud Platform (GCP)

      • IBM Cloud

      • Microsoft Azure

      • Red Hat OpenStack Platform (RHOSP)

      • VMware vSphere

    • Shared resource CSI driver

    • CSI volume support for the OpenShift Container Platform build system

    • Swap memory on nodes

Additional resources

Enabling feature sets using the web console

You can use the OpenShift Container Platform web console to enable feature sets for all of the nodes in a cluster by editing the FeatureGate custom resource (CR).

Procedure

To enable feature sets:

  1. In the OpenShift Container Platform web console, switch to the AdministrationCustom Resource Definitions page.

  2. On the Custom Resource Definitions page, click FeatureGate.

  3. On the Custom Resource Definition Details page, click the Instances tab.

  4. Click the cluster feature gate, then click the YAML tab.

  5. Edit the cluster instance to add specific feature sets:

    Sample Feature Gate custom resource
    apiVersion: config.openshift.io/v1
    kind: FeatureGate
    metadata:
      name: cluster (1)
    ....
    
    spec:
      featureSet: TechPreviewNoUpgrade (2)
    1 The name of the FeatureGate CR must be cluster.
    2 Add the feature set that you want to enable:
    • TechPreviewNoUpgrade enables specific Technology Preview features.

    After you save the changes, new machine configs are created, the machine config pools are updated, and scheduling on each node is disabled while the change is being applied.

    Enabling the TechPreviewNoUpgrade feature set cannot be undone and prevents minor version updates. These feature sets are not recommended on production clusters.

Verification

You can verify that the feature gates are enabled by looking at the kubelet.conf file on a node after the nodes return to the ready state.

  1. From the Administrator perspective in the web console, navigate to ComputeNodes.

  2. Select a node.

  3. In the Node details page, click Terminal.

  4. In the terminal window, change your root directory to the host:

    sh-4.2# chroot /host
  5. View the kubelet.conf file:

    sh-4.2# cat /etc/kubernetes/kubelet.conf
    Sample output
     ...
    featureGates:
      InsightsOperatorPullingSCA: true,
      LegacyNodeRoleBehavior: false
     ...

    The features that are listed as true are enabled on your cluster.

    The features listed vary depending upon the OpenShift Container Platform version.

Enabling feature sets using the CLI

You can use the OpenShift CLI (oc) to enable feature sets for all of the nodes in a cluster by editing the FeatureGate custom resource (CR).

Prerequisites
  • You have installed the OpenShift CLI (oc).

Procedure

To enable feature sets:

  1. Edit the FeatureGate CR named cluster:

    $ oc edit featuregate cluster
    Sample FeatureGate custom resource
    apiVersion: config.openshift.io/v1
    kind: FeatureGate
    metadata:
      name: cluster (1)
    spec:
      featureSet: TechPreviewNoUpgrade (2)
    1 The name of the FeatureGate CR must be cluster.
    2 Add the feature set that you want to enable:
    • TechPreviewNoUpgrade enables specific Technology Preview features.

    After you save the changes, new machine configs are created, the machine config pools are updated, and scheduling on each node is disabled while the change is being applied.

    Enabling the TechPreviewNoUpgrade feature set cannot be undone and prevents minor version updates. These feature sets are not recommended on production clusters.

Verification

You can verify that the feature gates are enabled by looking at the kubelet.conf file on a node after the nodes return to the ready state.

  1. Start a debug session for a node:

    $ oc debug node/<node_name>
  2. Change your root directory to the host:

    sh-4.2# chroot /host
  3. View the kubelet.conf file:

    sh-4.2# cat /etc/kubernetes/kubelet.conf
    Sample output
     ...
    featureGates:
      InsightsOperatorPullingSCA: true,
      LegacyNodeRoleBehavior: false
     ...

    The features that are listed as true are enabled on your cluster.

    The features listed vary depending upon the OpenShift Container Platform version.