Merge pull request #55259 from ironcladlou/gc-partial-discovery

Automatic merge from submit-queue. 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>.

Tolerate partial discovery in garbage collector

Allow the garbage collector to tolerate partial discovery failures. On a
partial failure, use whatever was discovered, log the failures, and
allow the resync logic to try again later.

Fixes #55022.

```release-note
API discovery failures no longer crash the kube controller manager via the garbage collector.
```

/cc @caesarxuchao

cmd/kube-controller-manager/app/core.go

@@ -348,10 +348,7 @@ func startGarbageCollectorController(ctx ControllerContext) (bool, error) {
 	clientPool := dynamic.NewClientPool(config, restMapper, dynamic.LegacyAPIPathResolverFunc)
 
 	// Get an initial set of deletable resources to prime the garbage collector.
-	deletableResources, err := garbagecollector.GetDeletableResources(discoveryClient)
-	if err != nil {
-		return true, err
-	}
+	deletableResources := garbagecollector.GetDeletableResources(discoveryClient)
 	ignoredResources := make(map[schema.GroupResource]struct{})
 	for _, r := range ctx.Options.GCIgnoredResources {
 		ignoredResources[schema.GroupResource{Group: r.Group, Resource: r.Resource}] = struct{}{}