explicit kubelet config key in Node.Spec.ConfigSource.ConfigMap

This makes the Kubelet config key in the ConfigMap an explicit part of
the API, so we can stop using magic key names.

As part of this change, we are retiring ConfigMapRef for ConfigMap.

test/e2e_node/util.go

@@ -57,8 +57,10 @@ var startServices = flag.Bool("start-services", true, "If true, start local node
 var stopServices = flag.Bool("stop-services", true, "If true, stop local node services after running tests")
 var busyboxImage = "busybox"
 
-// Kubelet internal cgroup name for node allocatable cgroup.
-const defaultNodeAllocatableCgroup = "kubepods"
+const (
+	// Kubelet internal cgroup name for node allocatable cgroup.
+	defaultNodeAllocatableCgroup = "kubepods"
+)
 
 func getNodeSummary() (*stats.Summary, error) {
 	req, err := http.NewRequest("GET", *kubeletAddress+"/stats/summary", nil)
@@ -167,10 +169,11 @@ func setKubeletConfiguration(f *framework.Framework, kubeCfg *kubeletconfig.Kube
 
 	// create the reference and set Node.Spec.ConfigSource
 	src := &apiv1.NodeConfigSource{
-		ConfigMapRef: &apiv1.ObjectReference{
-			Namespace: "kube-system",
-			Name:      cm.Name,
-			UID:       cm.UID,
+		ConfigMap: &apiv1.ConfigMapNodeConfigSource{
+			Namespace:        "kube-system",
+			Name:             cm.Name,
+			UID:              cm.UID,
+			KubeletConfigKey: "kubelet",
 		},
 	}