Separate labels and selector in services for clarity

pkg/api/types.go

@@ -138,11 +138,17 @@ type ServiceList struct {
 }
 
 // Defines a service abstraction by a name (for example, mysql) consisting of local port
-// (for example 3306) that the proxy listens on, and the labels that define the service.
+// (for example 3306) that the proxy listens on, and the selector that determines which pods
+// will answer requests sent through the proxy.
 type Service struct {
-	JSONBase                   `json:",inline" yaml:",inline"`
-	Port                       int               `json:"port,omitempty" yaml:"port,omitempty"`
-	Labels                     map[string]string `json:"labels,omitempty" yaml:"labels,omitempty"`
+	JSONBase `json:",inline" yaml:",inline"`
+	Port     int `json:"port,omitempty" yaml:"port,omitempty"`
+
+	// This service's labels.
+	Labels map[string]string `json:"labels,omitempty" yaml:"labels,omitempty"`
+
+	// This service will route traffic to pods having labels matching this selector.
+	Selector                   map[string]string `json:"selector,omitempty" yaml:"selector,omitempty"`
 	CreateExternalLoadBalancer bool              `json:"createExternalLoadBalancer,omitempty" yaml:"createExternalLoadBalancer,omitempty"`
 }
 

pkg/cloudcfg/cloudcfg.go

@@ -255,6 +255,9 @@ func createService(name string, port int, client client.ClientInterface) (api.Se
 		Labels: map[string]string{
 			"name": name,
 		},
+		Selector: map[string]string{
+			"name": name,
+		},
 	}
 	svc, err := client.CreateService(svc)
 	return svc, err

pkg/cloudcfg/parse_test.go

@@ -63,6 +63,9 @@ func TestParseService(t *testing.T) {
 		Labels: map[string]string{
 			"area": "staging",
 		},
+		Selector: map[string]string{
+			"area": "staging",
+		},
 	})
 }
 

pkg/cloudcfg/resource_printer.go

@@ -24,6 +24,7 @@ import (
 	"text/tabwriter"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 	"gopkg.in/v1/yaml"
 )
 
@@ -62,7 +63,7 @@ type HumanReadablePrinter struct{}
 
 var podColumns = []string{"Name", "Image(s)", "Host", "Labels"}
 var replicationControllerColumns = []string{"Name", "Image(s)", "Label Query", "Replicas"}
-var serviceColumns = []string{"Name", "Label Query", "Port"}
+var serviceColumns = []string{"Name", "Labels", "Selector", "Port"}
 
 func (h *HumanReadablePrinter) unknown(data string, w io.Writer) error {
 	_, err := fmt.Fprintf(w, "Unknown object: %s", data)
@@ -89,17 +90,9 @@ func (h *HumanReadablePrinter) makeImageList(manifest api.ContainerManifest) str
 	return strings.Join(images, ",")
 }
 
-func (h *HumanReadablePrinter) makeLabelsList(labels map[string]string) string {
-	var vals []string
-	for key, value := range labels {
-		vals = append(vals, fmt.Sprintf("%s=%s", key, value))
-	}
-	return strings.Join(vals, ",")
-}
-
 func (h *HumanReadablePrinter) printPod(pod api.Pod, w io.Writer) error {
 	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%s\n",
-		pod.ID, h.makeImageList(pod.DesiredState.Manifest), pod.CurrentState.Host+"/"+pod.CurrentState.HostIP, h.makeLabelsList(pod.Labels))
+		pod.ID, h.makeImageList(pod.DesiredState.Manifest), pod.CurrentState.Host+"/"+pod.CurrentState.HostIP, labels.Set(pod.Labels))
 	return err
 }
 
@@ -114,7 +107,7 @@ func (h *HumanReadablePrinter) printPodList(podList api.PodList, w io.Writer) er
 
 func (h *HumanReadablePrinter) printReplicationController(ctrl api.ReplicationController, w io.Writer) error {
 	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%d\n",
-		ctrl.ID, h.makeImageList(ctrl.DesiredState.PodTemplate.DesiredState.Manifest), h.makeLabelsList(ctrl.DesiredState.ReplicasInSet), ctrl.DesiredState.Replicas)
+		ctrl.ID, h.makeImageList(ctrl.DesiredState.PodTemplate.DesiredState.Manifest), labels.Set(ctrl.DesiredState.ReplicasInSet), ctrl.DesiredState.Replicas)
 	return err
 }
 
@@ -128,7 +121,7 @@ func (h *HumanReadablePrinter) printReplicationControllerList(list api.Replicati
 }
 
 func (h *HumanReadablePrinter) printService(svc api.Service, w io.Writer) error {
-	_, err := fmt.Fprintf(w, "%s\t%s\t%d\n", svc.ID, h.makeLabelsList(svc.Labels), svc.Port)
+	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%d\n", svc.ID, labels.Set(svc.Labels), labels.Set(svc.Selector), svc.Port)
 	return err
 }
 

pkg/labels/labels.go

@@ -45,3 +45,8 @@ func (ls Set) String() string {
 func (ls Set) Get(label string) string {
 	return ls[label]
 }
+
+// Convenience function: convert these labels to a query.
+func (ls Set) AsQuery() Query {
+	return QueryFromSet(ls)
+}

pkg/registry/endpoints.go

@@ -13,6 +13,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
+
 package registry
 
 import (
@@ -42,7 +43,7 @@ func (e *EndpointController) SyncServiceEndpoints() error {
 	}
 	var resultErr error
 	for _, service := range services.Items {
-		pods, err := e.podRegistry.ListPods(labels.QueryFromSet(labels.Set(service.Labels)))
+		pods, err := e.podRegistry.ListPods(labels.Set(service.Selector).AsQuery())
 		if err != nil {
 			log.Printf("Error syncing service: %#v, skipping.", service)
 			resultErr = err

pkg/registry/endpoints_test.go

@@ -49,7 +49,7 @@ func TestSyncEndpointsItems(t *testing.T) {
 		list: api.ServiceList{
 			Items: []api.Service{
 				{
-					Labels: map[string]string{
+					Selector: map[string]string{
 						"foo": "bar",
 					},
 				},
@@ -92,7 +92,7 @@ func TestSyncEndpointsPodError(t *testing.T) {
 		list: api.ServiceList{
 			Items: []api.Service{
 				{
-					Labels: map[string]string{
+					Selector: map[string]string{
 						"foo": "bar",
 					},
 				},

pkg/registry/etcd_registry_test.go

@@ -604,16 +604,21 @@ func TestEtcdUpdateService(t *testing.T) {
 	fakeClient := util.MakeFakeEtcdClient(t)
 	fakeClient.Set("/registry/services/specs/foo", util.MakeJSONString(api.Service{JSONBase: api.JSONBase{ID: "foo"}}), 0)
 	registry := MakeTestEtcdRegistry(fakeClient, []string{"machine"})
-	err := registry.UpdateService(api.Service{
+	testService := api.Service{
 		JSONBase: api.JSONBase{ID: "foo"},
 		Labels: map[string]string{
 			"baz": "bar",
 		},
-	})
+		Selector: map[string]string{
+			"baz": "bar",
+		},
+	}
+	err := registry.UpdateService(testService)
 	expectNoError(t, err)
 	svc, err := registry.GetService("foo")
-	if svc.Labels["baz"] != "bar" {
-		t.Errorf("Unexpected service: %#v", svc)
+	expectNoError(t, err)
+	if !reflect.DeepEqual(*svc, testService) {
+		t.Errorf("Unexpected service: got %#v, wanted %#v", svc, testService)
 	}
 }