Activating and deactivating feature gates¶

KubeVirt has a set of features that are not mature enough to be enabled by default. As such, they are protected by a Kubernetes concept called feature gates.

List of feature gates¶

The list of feature gates (which evolve in time) can be checked directly from the source code (use the const string values in the yaml configuration).

How to activate a feature gate¶

You can activate a specific feature gate directly in KubeVirt's CR, by provisioning the following yaml, which uses the ExperimentalFeatureToEnable feature gate as an example:

cat << END > enable-feature-gate.yaml
---
apiVersion: kubevirt.io/v1
kind: KubeVirt
metadata:
  name: kubevirt
  namespace: kubevirt
spec:
  configuration:
    developerConfiguration:
      featureGates:
        - ExperimentalFeatureToEnable
END

kubectl apply -f enable-feature-gate.yaml

Alternatively, the existing kubevirt CR can be altered:

kubectl edit kubevirt kubevirt -n kubevirt

...
spec:
  configuration:
    developerConfiguration:
      featureGates:
        - ExperimentalFeatureToEnable

Note: the name of the feature gates is case sensitive.

The snippet above assumes KubeVirt is installed in the kubevirt namespace. Change the namespace to suite your installation.

How to disable a feature gate¶

Starting from KubeVirt v1.8, you can explicitly disable feature gates using the disabledFeatureGates field. This is particularly useful when you want to disable beta features that may be enabled by default.

To disable specific feature gates, add them to the disabledFeatureGates list:

cat << END > disable-feature-gate.yaml
---
apiVersion: kubevirt.io/v1
kind: KubeVirt
metadata:
  name: kubevirt
  namespace: kubevirt
spec:
  configuration:
    developerConfiguration: 
      featureGates:
        - ExperimentalFeatureToEnable
      disabledFeatureGates:
        - ExperimentalFeatureToDisable
END

kubectl apply -f disable-feature-gate.yaml

Alternatively, edit the existing KubeVirt CR:

kubectl edit kubevirt kubevirt -n kubevirt

...
spec:
  configuration:
    developerConfiguration:
      featureGates:
        - ExperimentalFeatureToEnable
      disabledFeatureGates:
        - ExperimentalFeatureToDisable

Important

A feature gate cannot be listed in both featureGates and disabledFeatureGates at the same time. This will result in a validation error.