Merge pull request #56008 from xiangpengzhao/kubeadm-dkc-panic

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>.

Fix panic when assigning configmap UID of kubelet configuration.

**What this PR does / why we need it**:

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes https://github.com/kubernetes/kubeadm/issues/553

**Special notes for your reviewer**:
/cc @luxas 

**Release note**:

```release-note
NONE
```

cmd/kubeadm/app/phases/kubelet/kubelet.go

@@ -86,7 +86,13 @@ func UpdateNodeWithConfigMap(client clientset.Interface, nodeName string) error
 			return false, nil
 		}
 
-		node.Spec.ConfigSource.ConfigMapRef.UID = kubeletCfg.UID
+		node.Spec.ConfigSource = &v1.NodeConfigSource{
+			ConfigMapRef: &v1.ObjectReference{
+				Name:      kubeadmconstants.KubeletBaseConfigurationConfigMap,
+				Namespace: metav1.NamespaceSystem,
+				UID:       kubeletCfg.UID,
+			},
+		}
 
 		newData, err := json.Marshal(node)
 		if err != nil {