Enabling Feature Gates and APIs in a kind cluster

kind Kubernetes kind feature gate

3 min read | by Jordi Prats

Feature gates are a set of settings that can be used to enable or disable experimental features in Kubernetes. We can enable or disable features that are in alpha or beta stages of development. We need to keep in mind that these features are not yet stable and are not ready for production use.

In the Kubernetes documentation we can find the list of available feature gates. We are going to use MutatingAdmissionPolicy as an example.

To enable this feature in a kind cluster, we need to set the featureGates and runtimeConfig fields in the cluster configuration file:

  • Enable feature gates: This field is going to enable the feature that we want to use. To do so, we are going to use the featureGates field in the cluster configuration file.
  • Enable alpha API: This field is going to enable the alpha API that we want to use. To do so, we are going to use the runtimeConfig field in the cluster configuration file. We can get the API version from the object definition (or the Kubernetes documentation).

Here is an example of a cluster configuration file that is enabling the feature gate and the alpha API for the MutatingAdmissionPolicy feature:

kind: Cluster apiVersion: kind.x-k8s.io/v1alpha4 featureGates:  "MutatingAdmissionPolicy": true runtimeConfig:  "admissionregistration.k8s.io/v1alpha1": true

We can use kind create cluster with the --config parameter to create the cluster:

$ kind create cluster --config mutatingadmissionpolicy.yaml Creating cluster "kind" ...  ✓ Ensuring node image (kindest/node:v1.32.0) đŸ–ŧ  ✓ Preparing nodes đŸ“Ļ  ✓ Writing configuration 📜  ✓ Starting control-plane 🕹ī¸  ✓ Installing CNI 🔌  ✓ Installing StorageClass 💾 Set kubectl context to "kind-kind" You can now use your cluster with: kubectl cluster-info --context kind-kind Have a nice day! 👋

Once ready, we can validate that the feature is enabled by checking the kube-apiserver pod in the kube-system namespace:

$ kubectl get pod -n kube-system -l component=kube-apiserver -o yaml | grep feature-gates  - --feature-gates=MutatingAdmissionPolicy=true

To validate that we have enabled the alpha API, we can use the kubectl explain command on any object beloging to the API group, for example the MutatingAdmissionPolicy object that we are interested in:

$ k explain MutatingAdmissionPolicy KIND: MutatingAdmissionPolicy VERSION: admissionregistration.k8s.io/v1alpha1  DESCRIPTION:  MutatingAdmissionPolicy describes the definition of an admission mutation  policy that mutates the object coming into admission chain. FIELDS:  apiVersion <string>  APIVersion defines the versioned schema of this representation of an  object. Servers should convert recognized schemas to the latest internal  value, and may reject unrecognized values. More info:  https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources  kind <string>  Kind is a string value representing the REST resource this object  represents. Servers may infer this from the endpoint the client submits  requests to. Cannot be updated. In CamelCase. More info:  https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds  metadata <Object>  Standard object metadata; More info:  https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata.  spec <Object>  Specification of the desired behavior of the MutatingAdmissionPolicy.

Posted on 10/02/2025

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