aggregation: add ExternalName service support

Kubernetes-commit: 8b409e8f777a305454616554c40c905acad596ac

pkg/util/proxy/proxy.go

@@ -113,6 +113,14 @@ func ResolveCluster(services listersv1.ServiceLister, namespace, id string) (*ur
 			Scheme: "https",
 			Host:   net.JoinHostPort(svc.Spec.ClusterIP, fmt.Sprintf("%d", svcPort.Port)),
 		}, nil
+	case svc.Spec.Type == v1.ServiceTypeExternalName:
+		if port.Type != intstr.Int {
+			return nil, fmt.Errorf("named ports not supported")
+		}
+		return &url.URL{
+			Scheme: "https",
+			Host:   net.JoinHostPort(svc.Spec.ExternalName, port.String()),
+		}, nil
 	default:
 		return nil, fmt.Errorf("unsupported service type %q", svc.Spec.Type)
 	}

pkg/util/proxy/proxy_test.go

@@ -174,6 +174,22 @@ func TestResolve(t *testing.T) {
 			clusterMode:  expectation{url: "https://np:443"},
 			endpointMode: expectation{url: "https://127.0.0.1:1443"},
 		},
+		{
+			name: "external name",
+			services: []*v1.Service{
+				{
+					ObjectMeta: metav1.ObjectMeta{Namespace: "one", Name: "alfa"},
+					Spec: v1.ServiceSpec{
+						Type:         v1.ServiceTypeExternalName,
+						ExternalName: "foo.bar.com",
+					},
+				},
+			},
+			endpoints: nil,
+
+			clusterMode:  expectation{url: "https://foo.bar.com:443"},
+			endpointMode: expectation{error: true},
+		},
 		{
 			name:      "missing service",
 			services:  nil,