current CRDs aren't valid with the new GA-version of apiextensions.k8s.io/v1

[bavarianbidi]

Describe the bug
Since kubernetes 1.16 the apiextensions.k8s.io/v1beta1 is deprecated and will be unavailable in 1.22.
Deploying a CRD with apiextension.k8s.io/v1beta1 via kubectl leads to following warning:

Warning: apiextensions.k8s.io/v1beta1 CustomResourceDefinition is deprecated in v1.16+, unavailable in v1.22+; use apiextensions.k8s.io/v1 CustomResourceDefinition
customresourcedefinition.apiextensions.k8s.io/khjobs.comcast.github.io created

Steps To Reproduce

• Create a cluster with version 1.19 or 1.20 (kind create cluster)
  and run

  cat << EOF | kubectl apply -f -
  apiVersion: apiextensions.k8s.io/v1beta1
  kind: CustomResourceDefinition
  metadata:
    name: khstates.comcast.github.io
  spec:
    group: comcast.github.io
    version: v1
    scope: Namespaced
    names:
      plural: khstates
      singular: khstate
      kind: KuberhealthyState
      shortNames:
        - khs
   EOF
  

Expected behavior
No warning message

Additional context

But with some autogenerated CRDs we could use controller-gen from Kubebuilder.
Maybe useful to solve #603

following CRD-definition works for now:

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: khchecks.comcast.github.io
spec:
  group: comcast.github.io
  versions:
  - name: v1
    served: true
    storage: true
    schema:
      openAPIV3Schema:
        type: object
        x-kubernetes-embedded-resource: true
        x-kubernetes-preserve-unknown-fields: true
  scope: Namespaced
  names:
    plural: khchecks
    singular: khcheck
    kind: KuberhealthyCheck
    shortNames:
      - khc
---
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: khstates.comcast.github.io
spec:
  group: comcast.github.io
  versions:
  - name: v1
    served: true
    storage: true
    schema:
      openAPIV3Schema:
        type: object
        x-kubernetes-embedded-resource: true
        x-kubernetes-preserve-unknown-fields: true
  scope: Namespaced
  names:
    plural: khstates
    singular: khstate
    kind: KuberhealthyState
    shortNames:
      - khs
---
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: khjobs.comcast.github.io
spec:
  group: comcast.github.io
  versions:
  - name: v1
    served: true
    storage: true
    schema:
      openAPIV3Schema:
        type: object
        x-kubernetes-embedded-resource: true
        x-kubernetes-preserve-unknown-fields: true
  scope: Namespaced
  names:
    plural: khjobs
    singular: khjob
    kind: KuberhealthyJob
    shortNames:
      - khj

[integrii]

We need to figure out what the minimum supported version of apiextensions.k8s.io/v1 is, and then list our compatibility matrix in our readme. This way users know which versions of Kuberhealthy support which versions of Kubernetes.

Then, we need to make the apiVersion change and run things through some tests so that we are sure everything still works. After that, we can push this out in a release.

I am moving this from a bug to a feature request.

[integrii]

Part of PR #937