Bug 1811211

Somehow submitted without description:
Recent changes to kubeletcfg manifests seem to have broken our kubeletcfgs. This is on a cluster using master.

When I create a new kubelet config from https://github.com/openshift/machine-config-operator/blob/master/docs/KubeletConfigDesign.md#spec

apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  name: set-max-pods
spec:
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: small-pods
  kubeletConfig:
    maxPods: 100

I see errors:

The KubeletConfig "set-max-pods" is invalid: 
* spec.kubeletConfig.apiVersion: Required value: must not be empty
* spec.kubeletConfig.kind: Required value: must not be empty

I just ran into this today. I think it's due to the spec.kubeletConfig type changing from
kubeletconfigv1beta1.KubeletConfiguration to runtime.RawExtension which requires a kind and apiVersion.

So the above KubeletConfig needs to change to something like this:

apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  name: set-max-pods
spec:
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: small-pods
  kubeletConfig:
    apiVersion: kubelet.config.k8s.io/v1beta1
    kind: KubeletConfiguration
    maxPods: 100

I'm not sure if the bug is that we need to change our docs to reflect this change, or if there is something missing that would make it work without specifying apiVersion and kind.  This bug is probably related to bug 1809274 and possibly a duplicate of it.

*** Bug 1811493 has been marked as a duplicate of this bug. ***

To verify fix:

Without the fix do what I did here: https://bugzilla.redhat.com/show_bug.cgi?id=1811211#c1

With fix do the same thing and see no error...

Verified on 4.5.0-0.nightly-2020-03-12-003015

$ oc get clusterversion
NAME      VERSION                             AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.5.0-0.nightly-2020-03-12-003015   True        False         5m57s   Cluster version is 4.5.0-0.nightly-2020-03-12-003015
$ oc get mcp/worker
NAME     CONFIG                                             UPDATED   UPDATING   DEGRADED   MACHINECOUNT   READYMACHINECOUNT   UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
worker   rendered-worker-f8d09e1f704c4a0082dcc797c967d9c5   True      False      False      3              3                   3                     0                      22m
$ oc label mcp/worker custom-kubelet=small-pods
machineconfigpool.machineconfiguration.openshift.io/worker labeled
$ oc get mcp/worker -o yaml | head -20
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfigPool
metadata:
  creationTimestamp: "2020-03-12T03:25:33Z"
  generation: 2
  labels:
    custom-kubelet: small-pods
    machineconfiguration.openshift.io/mco-built-in: ""
  name: worker
  resourceVersion: "23391"
  selfLink: /apis/machineconfiguration.openshift.io/v1/machineconfigpools/worker
  uid: 242e164b-1166-4ba8-9b7a-f32421138985
spec:
  configuration:
    name: rendered-worker-f8d09e1f704c4a0082dcc797c967d9c5
    source:
    - apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      name: 00-worker
    - apiVersion: machineconfiguration.openshift.io/v1
$ cat << EOF > small-pods.yaml
apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  name: set-max-pods
spec:
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: small-pods
  kubeletConfig:
    maxPods: 100
EOF
$ oc apply -f small-pods.yaml 
kubeletconfig.machineconfiguration.openshift.io/set-max-pods created
$ oc get kubeletconfig
NAME           AGE
set-max-pods   11s
$ oc get kubeletconfig/set-max-pods -o yaml
apiVersion: machineconfiguration.openshift.io/v1
kind: KubeletConfig
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"machineconfiguration.openshift.io/v1","kind":"KubeletConfig","metadata":{"annotations":{},"name":"set-max-pods"},"spec":{"kubeletConfig":{"maxPods":100},"machineConfigPoolSelector":{"matchLabels":{"custom-kubelet":"small-pods"}}}}
  creationTimestamp: "2020-03-12T03:49:16Z"
  finalizers:
  - f94bd0cd-63e1-40ff-8a98-cd5c1a8b4ab4
  generation: 1
  name: set-max-pods
  resourceVersion: "23539"
  selfLink: /apis/machineconfiguration.openshift.io/v1/kubeletconfigs/set-max-pods
  uid: 4532f227-d248-4007-92c7-0ad7d858544e
spec:
  kubeletConfig:
    maxPods: 100
  machineConfigPoolSelector:
    matchLabels:
      custom-kubelet: small-pods
status:
  conditions:
  - lastTransitionTime: "2020-03-12T03:49:16Z"
    message: Success
    status: "True"
    type: Success

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:2409