let kubectl annotate use patch instead of replace

pkg/kubectl/cmd/annotate.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"io"
 	"strings"
@@ -28,6 +29,7 @@ import (
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 	"k8s.io/kubernetes/pkg/kubectl/resource"
 	"k8s.io/kubernetes/pkg/runtime"
+	"k8s.io/kubernetes/pkg/util/strategicpatch"
 )
 
 // AnnotateOptions have the data required to perform the annotate operation
@@ -91,7 +93,7 @@ func NewCmdAnnotate(f *cmdutil.Factory, out io.Writer) *cobra.Command {
 			if err := options.Validate(args); err != nil {
 				cmdutil.CheckErr(cmdutil.UsageError(cmd, err.Error()))
 			}
-			if err := options.RunAnnotate(); err != nil {
+			if err := options.RunAnnotate(f); err != nil {
 				cmdutil.CheckErr(err)
 			}
 		},
@@ -167,26 +169,43 @@ func (o AnnotateOptions) Validate(args []string) error {
 }
 
 // RunAnnotate does the work
-func (o AnnotateOptions) RunAnnotate() error {
+func (o AnnotateOptions) RunAnnotate(f *cmdutil.Factory) error {
 	r := o.builder.Do()
 	if err := r.Err(); err != nil {
 		return err
 	}
+
 	return r.Visit(func(info *resource.Info, err error) error {
 		if err != nil {
 			return err
 		}
-		_, uErr := cmdutil.UpdateObject(info, func(obj runtime.Object) error {
-			err := o.updateAnnotations(obj)
-			if err != nil {
-				return err
-			}
-			return nil
-		})
-		if uErr != nil {
-			return uErr
+
+		name, namespace, obj := info.Name, info.Namespace, info.Object
+		oldData, err := json.Marshal(obj)
+		if err != nil {
+			return err
 		}
-		return nil
+		if err := o.updateAnnotations(obj); err != nil {
+			return err
+		}
+		newData, err := json.Marshal(obj)
+		if err != nil {
+			return err
+		}
+		patchBytes, err := strategicpatch.CreateTwoWayMergePatch(oldData, newData, obj)
+		if err != nil {
+			return err
+		}
+
+		mapping := info.ResourceMapping()
+		client, err := f.RESTClient(mapping)
+		if err != nil {
+			return err
+		}
+		helper := resource.NewHelper(client, mapping)
+
+		_, err = helper.Patch(namespace, name, api.StrategicMergePatchType, patchBytes)
+		return err
 	})
 }