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Understanding FeatureGates and Technology Preview features

You can use the FeatureGates Custom Resource to toggle on and off Technology Preview features throughout your cluster.

This allows you, for example, to ensure that Technology Preview features are off for production clusters while leaving the features on for test clusters where you can fully test them.

Features that are affected by FeatureGates

The following features are affected by FeatureGates:

FeatureGate Description Default

ExperimentalCriticalPodAnnotation

Enables annotating specific Pods as critical so that their scheduling is guaranteed.

True

RotateKubeletServerCertificate

Enables the rotation of the server TLS certificate on the cluster.

True

SupportPodPidsLimit

Enables support for limiting the number of processes (PIDs) running in a Pod.

True

MachineHealthCheck

Enables automatically repairing unhealthy machines in a machine pool.

True

LocalStorageCapacityIsolation

Enable the consumption of local ephemeral storage and also the sizeLimit property of an emptyDir volume.

False

You can enable these features by editing the Feature Gate Custom Resource. Turning on these features cannot be undone and prevents the ability to upgrade your cluster.

The LocalStorageCapacityIsolation cannot be enabled.

Enabling Technology Preview features using FeatureGates

You can turn Technology Preview features on and off for all nodes in the cluster by editing the FeatureGates Custom Resource, named cluster, in the openshift-config project.

The following Technology Preview features are enabled by feature gates:

  • ExperimentalCriticalPodAnnotation

  • RotateKubeletServerCertificate

  • SupportPodPidsLimit

  • MachineHealthCheck

Turning on Technology Preview features cannot be undone and prevents upgrades.

Procedure

To turn on the Technology Preview features for the entire cluster:

  1. Create the FeatureGates instance:

    1. Switch to the AdministrationCustom Resource Definitions page.

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

    3. On the Custom Resource Definitions page, click the Actions Menu and select View Instances.

    4. On the Feature Gates page, click Create Feature Gates.

    5. Replace the code with following sample:

      apiVersion: config.openshift.io/v1
      kind: FeatureGate
      metadata:
        name: cluster
      spec: {}
    6. Click Create.

  2. To turn on the Technology Preview features, change the spec parameter to:

    apiVersion: config.openshift.io/v1
    kind: FeatureGate
    metadata:
      name: cluster
    spec:
      featureSet: TechPreviewNoUpgrade (1)
    1 Add featureSet: TechPreviewNoUpgrade to enable the Technology Preview features that are affected by FeatureGates.

    Turning on Technology Preview features cannot be undone and prevents upgrades.