expose: Re-use labels in case none was specified

docs/kubectl_expose.md

@@ -8,7 +8,8 @@ Take a replicated application and expose it as Kubernetes Service
 Take a replicated application and expose it as Kubernetes Service.
 
 Looks up a replication controller or service by name and uses the selector for that resource as the
-selector for a new Service on the specified port.
+selector for a new Service on the specified port. If no labels are specified, the new service will
+re-use the labels from the resource it exposes.
 
 ```
 kubectl expose RESOURCE NAME --port=port [--protocol=TCP|UDP] [--target-port=number-or-name] [--service-name=name] [--public-ip=ip] [--create-external-load-balancer=bool]
@@ -81,4 +82,4 @@ $ kubectl expose rc streamer --port=4100 --protocol=udp --service-name=video-str
 ### SEE ALSO
 * [kubectl](kubectl.md)	 - kubectl controls the Kubernetes cluster manager
 
-###### Auto generated by spf13/cobra at 2015-05-08 20:26:40.49295951 +0000 UTC
+###### Auto generated by spf13/cobra at 2015-05-14 09:05:28.99900833 +0000 UTC

docs/man/man1/kubectl-expose.1

@@ -17,7 +17,8 @@ Take a replicated application and expose it as Kubernetes Service.
 
 .PP
 Looks up a replication controller or service by name and uses the selector for that resource as the
-selector for a new Service on the specified port.
+selector for a new Service on the specified port. If no labels are specified, the new service will
+re\-use the labels from the resource it exposes.
 
 
 .SH OPTIONS

pkg/kubectl/cmd/expose.go

@@ -32,7 +32,8 @@ const (
 	expose_long = `Take a replicated application and expose it as Kubernetes Service.
 
 Looks up a replication controller or service by name and uses the selector for that resource as the
-selector for a new Service on the specified port.`
+selector for a new Service on the specified port. If no labels are specified, the new service will
+re-use the labels from the resource it exposes.`
 
 	expose_example = `// Creates a service for a replicated nginx, which serves on port 80 and connects to the containers on port 8000.
 $ kubectl expose rc nginx --port=80 --target-port=8000
@@ -151,6 +152,13 @@ func RunExpose(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []str
 	if cmdutil.GetFlagBool(cmd, "create-external-load-balancer") {
 		params["create-external-load-balancer"] = "true"
 	}
+	if len(params["labels"]) == 0 {
+		labels, err := f.LabelsForObject(inputObject)
+		if err != nil {
+			return err
+		}
+		params["labels"] = kubectl.MakeLabels(labels)
+	}
 	err = kubectl.ValidateParams(names, params)
 	if err != nil {
 		return err

pkg/kubectl/cmd/expose_test.go

@@ -41,13 +41,15 @@ func TestRunExposeService(t *testing.T) {
 			args: []string{"service", "baz"},
 			input: &api.Service{
 				ObjectMeta: api.ObjectMeta{Name: "baz", Namespace: "test", ResourceVersion: "12"},
+				TypeMeta:   api.TypeMeta{Kind: "Service", APIVersion: "v1beta3"},
 				Spec: api.ServiceSpec{
 					Selector: map[string]string{"app": "go"},
 				},
 			},
-			flags: map[string]string{"selector": "func=stream", "protocol": "UDP", "port": "14", "service-name": "foo"},
+			flags: map[string]string{"selector": "func=stream", "protocol": "UDP", "port": "14", "service-name": "foo", "labels": "svc=test"},
 			output: &api.Service{
-				ObjectMeta: api.ObjectMeta{Name: "foo", Namespace: "test", ResourceVersion: "12"},
+				ObjectMeta: api.ObjectMeta{Name: "foo", Namespace: "test", ResourceVersion: "12", Labels: map[string]string{"svc": "test"}},
+				TypeMeta:   api.TypeMeta{Kind: "Service", APIVersion: "v1beta3"},
 				Spec: api.ServiceSpec{
 					Ports: []api.ServicePort{
 						{

pkg/kubectl/cmd/util/factory.go

@@ -73,6 +73,8 @@ type Factory struct {
 	PodSelectorForObject func(object runtime.Object) (string, error)
 	// PortsForObject returns the ports associated with the provided object
 	PortsForObject func(object runtime.Object) ([]string, error)
+	// LabelsForObject returns the labels associated with the provided object
+	LabelsForObject func(object runtime.Object) (map[string]string, error)
 	// Returns a schema that can validate objects stored on disk.
 	Validator func() (validation.Schema, error)
 	// Returns the default namespace to use in cases where no other namespace is specified
@@ -182,6 +184,9 @@ func NewFactory(optionalClientConfig clientcmd.ClientConfig) *Factory {
 				return nil, fmt.Errorf("it is not possible to get ports from %s", kind)
 			}
 		},
+		LabelsForObject: func(object runtime.Object) (map[string]string, error) {
+			return meta.NewAccessor().Labels(object)
+		},
 		Resizer: func(mapping *meta.RESTMapping) (kubectl.Resizer, error) {
 			client, err := clients.ClientForVersion(mapping.APIVersion)
 			if err != nil {

pkg/kubectl/cmd/util/factory_test.go

@@ -23,6 +23,8 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/clientcmd"
 	clientcmdapi "github.com/GoogleCloudPlatform/kubernetes/pkg/client/clientcmd/api"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
 )
 
 func TestNewFactoryDefaultFlagBindings(t *testing.T) {
@@ -100,3 +102,54 @@ func TestPortsForObject(t *testing.T) {
 		}
 	}
 }
+
+func TestLabelsForObject(t *testing.T) {
+	f := NewFactory(nil)
+
+	tests := []struct {
+		name     string
+		object   runtime.Object
+		expected string
+		err      error
+	}{
+		{
+			name: "successful re-use of labels",
+			object: &api.Service{
+				ObjectMeta: api.ObjectMeta{Name: "baz", Namespace: "test", Labels: map[string]string{"svc": "test"}},
+				TypeMeta:   api.TypeMeta{Kind: "Service", APIVersion: "v1beta3"},
+			},
+			expected: "svc=test",
+			err:      nil,
+		},
+		{
+			name: "empty labels",
+			object: &api.Service{
+				ObjectMeta: api.ObjectMeta{Name: "foo", Namespace: "test", Labels: map[string]string{}},
+				TypeMeta:   api.TypeMeta{Kind: "Service", APIVersion: "v1beta3"},
+			},
+			expected: "",
+			err:      nil,
+		},
+		{
+			name: "nil labels",
+			object: &api.Service{
+				ObjectMeta: api.ObjectMeta{Name: "zen", Namespace: "test", Labels: nil},
+				TypeMeta:   api.TypeMeta{Kind: "Service", APIVersion: "v1beta3"},
+			},
+			expected: "",
+			err:      nil,
+		},
+	}
+
+	for _, test := range tests {
+		gotLabels, err := f.LabelsForObject(test.object)
+		if err != test.err {
+			t.Fatalf("%s: Error mismatch: Expected %v, got %v", test.name, test.err, err)
+		}
+		got := kubectl.MakeLabels(gotLabels)
+		if test.expected != got {
+			t.Fatalf("%s: Labels mismatch! Expected %s, got %s", test.name, test.expected, got)
+		}
+
+	}
+}

pkg/kubectl/service.go

@@ -32,6 +32,7 @@ func (ServiceGenerator) ParamNames() []GeneratorParam {
 		{"name", true},
 		{"selector", true},
 		{"port", true},
+		{"labels", false},
 		{"public-ip", false},
 		{"create-external-load-balancer", false},
 		{"protocol", false},