Merge pull request #30931 from Clarifai/ext-svc-ref-dns

Automatic merge from submit-queue

Add ExternalName kube-dns e2e test

ExternalName allows kubedns to return CNAME records for external
services. No proxying is involved.

Built on top of and includes #30599 

See original issue at
https://github.com/kubernetes/kubernetes/issues/13748

Feature tracking at
https://github.com/kubernetes/features/issues/33

The e2e test is at least as comprehensive as the one for headless services (namely, only to some degree)

```release-note
Add ExternalName services as CNAME references to external ones
```

cluster/addons/dns/skydns-rc.yaml.base

@@ -44,7 +44,7 @@ spec:
     spec:
       containers:
       - name: kubedns
-        image: gcr.io/google_containers/kubedns-amd64:1.6
+        image: gcr.io/google_containers/kubedns-amd64:1.7
         resources:
           # TODO: Set memory limits when we've profiled the container for large
           # clusters, then set request = limit to keep this container in

cluster/addons/dns/skydns-rc.yaml.in

@@ -44,7 +44,7 @@ spec:
     spec:
       containers:
       - name: kubedns
-        image: gcr.io/google_containers/kubedns-amd64:1.6
+        image: gcr.io/google_containers/kubedns-amd64:1.7
         resources:
           # TODO: Set memory limits when we've profiled the container for large
           # clusters, then set request = limit to keep this container in

cluster/addons/dns/skydns-rc.yaml.sed

@@ -44,7 +44,7 @@ spec:
     spec:
       containers:
       - name: kubedns
-        image: gcr.io/google_containers/kubedns-amd64:1.6
+        image: gcr.io/google_containers/kubedns-amd64:1.7
         resources:
           # TODO: Set memory limits when we've profiled the container for large
           # clusters, then set request = limit to keep this container in