Understanding feature gates and Technology Preview features

You can use the Feature Gate Custom Resource to enable Technology Preview features throughout your cluster. This allows you, for example, to enable Technology Preview features on test clusters where you can fully test them while ensuring they are disabled on production clusters.

After turning Technology Preview features on using feature gates, they cannot be turned off and cluster upgrades are prevented.

Features that are affected by FeatureGates

The following Technology Preview features included in OKD:

FeatureGate Description Default

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 feature gates

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

The following Technology Preview features are enabled by feature gates:

  • RotateKubeletServerCertificate

  • SupportPodPidsLimit

Turning on Technology Preview features using the Feature Gate Custom Resource cannot be undone and prevents upgrades.

Procedure

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

  1. In the OKD web sonsole, switch to the AdministrationCustom Resource Definitions page.

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

  3. On the Custom Resource Definitions page, click ActionsView Instances.

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

  5. Add the featureSet parameter:

    apiVersion: config.openshift.io/v1
    kind: FeatureGate
    metadata:
      name: cluster
    spec:
      featureSet: "TechPreviewNoUpgrade" (1)
    1 Add the featureSet: "TechPreviewNoUpgrade" parameter.
  6. Click Save.