Merge pull request kubernetes#67694 from sttts/sttts-kube-apiserver-always-create-extension-apiserver-authentication

Automatic merge from submit-queue (batch tested with PRs 67694, 64973, 67902). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

kube-apiserver: always create configmap/extension-apiserver-authentication

Other components (aggregated apiservers) read the configmap and fail hard if it does not exist. But they work without all fields being set (kubernetes#66394). In the future, components like ctrl-manager and scheduler won't need kube-apiserver to authenticate with them at all. So, consequently we should always create the file, even if it is empty.

```release-note
Always create configmaps/extensions-apiserver-authentication from kube-apiserver.
```

Author: Kubernetes Submit Queue

pkg/master/client_ca_hook.go

@@ -41,11 +41,6 @@ type ClientCARegistrationHook struct {
 }
 
 func (h ClientCARegistrationHook) PostStartHook(hookContext genericapiserver.PostStartHookContext) error {
-	// no work to do
-	if len(h.ClientCA) == 0 && len(h.RequestHeaderCA) == 0 {
-		return nil
-	}
-
 	// initializing CAs is important so that aggregated API servers can come up with "normal" config.
 	// We've seen lagging etcd before, so we want to retry this a few times before we decide to crashloop
 	// the API server on it.
@@ -68,7 +63,6 @@ func (h ClientCARegistrationHook) PostStartHook(hookContext genericapiserver.Pos
 	}
 
 	return nil
-
 }
 
 // tryToWriteClientCAs is here for unit testing with a fake client.  This is a wait.ConditionFunc so the bool