Allow headless svc without ports to have endpoints

As cited in
https://github.com/kubernetes/dns/issues/174 - this is documented to
work, and I don't see why it shouldn't work.  We allowed the definition
of headless services without ports, but apparently nobody tested it very
well.

Manually tested clusterIP services with no ports - validation error.

Manually tested services with negative ports - validation error.

New tests failed, output inspected and verified.  Now pass.

pkg/controller/endpoint/endpoints_controller_test.go

@@ -863,6 +863,34 @@ func TestSyncEndpointsItemsExcludeNotReadyPodsWithRestartPolicyOnFailureAndPhase
 	endpointsHandler.ValidateRequest(t, testapi.Default.ResourcePath("endpoints", ns, "foo"), "PUT", &data)
 }
 
+func TestSyncEndpointsHeadlessWithoutPort(t *testing.T) {
+	ns := metav1.NamespaceDefault
+	testServer, endpointsHandler := makeTestServer(t, ns)
+	defer testServer.Close()
+	endpoints := newController(testServer.URL)
+	endpoints.serviceStore.Add(&v1.Service{
+		ObjectMeta: metav1.ObjectMeta{Name: "foo", Namespace: ns},
+		Spec: v1.ServiceSpec{
+			Selector:  map[string]string{"foo": "bar"},
+			ClusterIP: "None",
+			Ports:     nil,
+		},
+	})
+	addPods(endpoints.podStore, ns, 1, 1, 0)
+	endpoints.syncService(ns + "/foo")
+	endpointsHandler.ValidateRequestCount(t, 1)
+	data := runtime.EncodeOrDie(testapi.Default.Codec(), &v1.Endpoints{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "foo",
+		},
+		Subsets: []v1.EndpointSubset{{
+			Addresses: []v1.EndpointAddress{{IP: "1.2.3.4", NodeName: &emptyNodeName, TargetRef: &v1.ObjectReference{Kind: "Pod", Name: "pod0", Namespace: ns}}},
+			Ports:     nil,
+		}},
+	})
+	endpointsHandler.ValidateRequest(t, testapi.Default.ResourcePath("endpoints", ns, ""), "POST", &data)
+}
+
 // There are 3*5 possibilities(3 types of RestartPolicy by 5 types of PodPhase). Not list them all here.
 // Just list all of the 3 false cases and 3 of the 12 true cases.
 func TestShouldPodBeInEndpoints(t *testing.T) {