Enabling features using FeatureGates - Working with clusters | Nodes

Understanding feature gates
Enabling feature sets using the web console
Enabling feature sets using the CLI

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 OKD features that are not enabled by default.

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

IPv6DualStackNoUpgrade. This feature gate enables the dual-stack networking mode in your cluster. Dual-stack networking supports the use of IPv4 and IPv6 simultaneously. Enabling this feature set is not supported, cannot be undone, and prevents updates. This feature set is not recommended on production clusters.

Enabling feature sets using the web console

You can use the OKD 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:

In the OKD web console, switch to the Administration → Custom Resource Definitions page.
On the Custom Resource Definitions page, click FeatureGate.
On the Custom Resource Definition Details page, click the Instances tab.
Click the cluster feature gate, then click the YAML tab.
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: IPv6DualStackNoUpgrade (2)
```
1 The name of the FeatureGate CR must be cluster.

2 Add the IPv6DualStackNoUpgrade feature set to enable the dual-stack networking mode.

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 IPv6DualStackNoUpgrade feature set cannot be undone and prevents updates. This feature set is 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.

From the Administrator perspective in the web console, navigate to Compute → Nodes.
Select a node.
In the Node details page, click Terminal.
In the terminal window, change your root directory to the host:
```
sh-4.2# chroot /host
```
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 OKD 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).