Add local option to the label command

This is to be used with the new "set selector" command.

hack/make-rules/test-cmd.sh

@@ -808,6 +808,16 @@ __EOF__
   [ "$(EDITOR=cat kubectl edit --windows-line-endings pod/valid-pod | file - | grep CRLF)" ]
   [ ! "$(EDITOR=cat kubectl edit --windows-line-endings=false pod/valid-pod | file - | grep CRLF)" ]
 
+  ### Label POD YAML file locally without effecting the live pod.
+  # Pre-condition: name is valid-pod
+  kube::test::get_object_assert 'pod valid-pod' "{{${labels_field}.name}}" 'valid-pod'
+  # Command
+  output_message=$(kubectl label --local --overwrite -f hack/testdata/pod.yaml name=localonlyvalue -o yaml "${kube_flags[@]}")
+  echo $output_message
+  # Post-condition: name is still valid-pod in the live pod, but command output is the new value
+  kube::test::get_object_assert 'pod valid-pod' "{{${labels_field}.name}}" 'valid-pod'
+  kube::test::if_has_string "${output_message}" "localonlyvalue"
+
   ### Overwriting an existing label is not permitted
   # Pre-condition: name is valid-pod
   kube::test::get_object_assert 'pod valid-pod' "{{${labels_field}.name}}" 'valid-pod'

pkg/kubectl/cmd/label.go

@@ -93,6 +93,7 @@ func NewCmdLabel(f *cmdutil.Factory, out io.Writer) *cobra.Command {
 	}
 	cmdutil.AddPrinterFlags(cmd)
 	cmd.Flags().Bool("overwrite", false, "If true, allow labels to be overwritten, otherwise reject label updates that overwrite existing labels.")
+	cmd.Flags().Bool("local", false, "If true, label will NOT contact api-server but run locally.")
 	cmd.Flags().StringP("selector", "l", "", "Selector (label query) to filter on")
 	cmd.Flags().Bool("all", false, "select all resources in the namespace of the specified resource types")
 	cmd.Flags().String("resource-version", "", "If non-empty, the labels update will only succeed if this is the current resource-version for the object. Only valid when specifying a single resource.")
@@ -188,6 +189,7 @@ func RunLabel(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []stri
 	all := cmdutil.GetFlagBool(cmd, "all")
 	overwrite := cmdutil.GetFlagBool(cmd, "overwrite")
 	resourceVersion := cmdutil.GetFlagString(cmd, "resource-version")
+	local := cmdutil.GetFlagBool(cmd, "local")
 
 	cmdNamespace, enforceNamespace, err := f.DefaultNamespace()
 	if err != nil {
@@ -203,11 +205,13 @@ func RunLabel(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []stri
 		ContinueOnError().
 		NamespaceParam(cmdNamespace).DefaultNamespace().
 		FilenameParam(enforceNamespace, options).
-		SelectorParam(selector).
+		Flatten()
-		ResourceTypeOrNameArgs(all, resources...).
-		Flatten().
-		Latest()
 
+	if !local {
+		b = b.SelectorParam(selector).
+			ResourceTypeOrNameArgs(all, resources...).
+			Latest()
+	}
 	one := false
 	r := b.Do().IntoSingular(&one)
 	if err := r.Err(); err != nil {
@@ -227,7 +231,7 @@ func RunLabel(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []stri
 
 		var outputObj runtime.Object
 		dataChangeMsg := "not labeled"
-		if cmdutil.GetDryRunFlag(cmd) {
+		if cmdutil.GetDryRunFlag(cmd) || local {
 			err = labelFunc(info.Object, overwrite, resourceVersion, lbls, remove)
 			if err != nil {
 				return err

pkg/kubectl/cmd/label_test.go

@@ -383,6 +383,34 @@ func TestLabelForResourceFromFile(t *testing.T) {
 	}
 }
 
+func TestLabelLocal(t *testing.T) {
+	f, tf, _, ns := NewAPIFactory()
+	tf.Client = &fake.RESTClient{
+		NegotiatedSerializer: ns,
+		Client: fake.CreateHTTPClient(func(req *http.Request) (*http.Response, error) {
+			t.Fatalf("unexpected request: %s %#v\n%#v", req.Method, req.URL, req)
+			return nil, nil
+		}),
+	}
+	tf.Namespace = "test"
+	tf.ClientConfig = &restclient.Config{ContentConfig: restclient.ContentConfig{GroupVersion: testapi.Default.GroupVersion()}}
+
+	buf := bytes.NewBuffer([]byte{})
+	cmd := NewCmdLabel(f, buf)
+	cmd.Flags().Set("local", "true")
+	options := &resource.FilenameOptions{
+		Filenames: []string{"../../../examples/storage/cassandra/cassandra-controller.yaml"},
+	}
+
+	err := RunLabel(f, buf, cmd, []string{"a=b"}, options)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !strings.Contains(buf.String(), "labeled") {
+		t.Errorf("did not set labels: %s", buf.String())
+	}
+}
+
 func TestLabelMultipleObjects(t *testing.T) {
 	pods, _, _ := testData()
 	f, tf, codec, ns := NewAPIFactory()