let patch use local file content to mutate

hack/test-cmd.sh

@@ -627,6 +627,9 @@ runTests() {
   # Post-condition: valid-pod POD is created
   kube::test::get_object_assert pods "{{range.items}}{{$id_field}}:{{end}}" 'valid-pod:'
 
+  ## Patch can modify a local object
+  kubectl patch --local -f pkg/api/validation/testdata/v1/validPod.yaml --patch='{"spec": {"restartPolicy":"Never"}}' -o jsonpath='{.spec.restartPolicy}' | grep -q "Never"
+
   ## Patch pod can change image
   # Command
   kubectl patch "${kube_flags[@]}" pod valid-pod --record -p='{"spec":{"containers":[{"name": "kubernetes-serve-hostname", "image": "nginx"}]}}'

pkg/kubectl/cmd/patch.go

@@ -21,13 +21,16 @@ import (
 	"io"
 	"strings"
 
+	"github.com/evanphx/json-patch"
 	"github.com/spf13/cobra"
 
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/kubectl"
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 	"k8s.io/kubernetes/pkg/kubectl/resource"
+	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/util/sets"
+	"k8s.io/kubernetes/pkg/util/strategicpatch"
 	"k8s.io/kubernetes/pkg/util/yaml"
 )
 
@@ -38,6 +41,9 @@ var patchTypes = map[string]api.PatchType{"json": api.JSONPatchType, "merge": ap
 type PatchOptions struct {
 	Filenames []string
 	Recursive bool
+	Local     bool
+
+	OutputFormat string
 }
 
 const (
@@ -78,9 +84,8 @@ func NewCmdPatch(f *cmdutil.Factory, out io.Writer) *cobra.Command {
 		Long:    patch_long,
 		Example: patch_example,
 		Run: func(cmd *cobra.Command, args []string) {
-			cmdutil.CheckErr(cmdutil.ValidateOutputArgs(cmd))
-			shortOutput := cmdutil.GetFlagString(cmd, "output") == "name"
-			err := RunPatch(f, out, cmd, args, shortOutput, options)
+			options.OutputFormat = cmdutil.GetFlagString(cmd, "output")
+			err := RunPatch(f, out, cmd, args, options)
 			cmdutil.CheckErr(err)
 		},
 		ValidArgs:  validArgs,
@@ -89,17 +94,25 @@ func NewCmdPatch(f *cmdutil.Factory, out io.Writer) *cobra.Command {
 	cmd.Flags().StringP("patch", "p", "", "The patch to be applied to the resource JSON file.")
 	cmd.MarkFlagRequired("patch")
 	cmd.Flags().String("type", "strategic", fmt.Sprintf("The type of patch being provided; one of %v", sets.StringKeySet(patchTypes).List()))
-	cmdutil.AddOutputFlagsForMutation(cmd)
+	cmdutil.AddPrinterFlags(cmd)
 	cmdutil.AddRecordFlag(cmd)
 	cmdutil.AddInclude3rdPartyFlags(cmd)
 
 	usage := "Filename, directory, or URL to a file identifying the resource to update"
 	kubectl.AddJsonFilenameFlag(cmd, &options.Filenames, usage)
 	cmdutil.AddRecursiveFlag(cmd, &options.Recursive)
+
+	cmd.Flags().BoolVar(&options.Local, "local", false, "If true, patch will operate on the content of the file, not the server-side resource.")
+
 	return cmd
 }
 
-func RunPatch(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []string, shortOutput bool, options *PatchOptions) error {
+func RunPatch(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []string, options *PatchOptions) error {
+	switch {
+	case options.Local && len(args) != 0:
+		return fmt.Errorf("cannot specify --local and server resources")
+	}
+
 	cmdNamespace, enforceNamespace, err := f.DefaultNamespace()
 	if err != nil {
 		return err
@@ -149,6 +162,7 @@ func RunPatch(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []stri
 			return err
 		}
 
+		if !options.Local {
 			helper := resource.NewHelper(client, mapping)
 			patchedObject, err := helper.Patch(namespace, name, patchType, patchBytes)
 			if err != nil {
@@ -164,7 +178,44 @@ func RunPatch(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []stri
 				}
 			}
 			count++
-		cmdutil.PrintSuccess(mapper, shortOutput, out, "", name, "patched")
+
+			if options.OutputFormat == "name" || len(options.OutputFormat) == 0 {
+				cmdutil.PrintSuccess(mapper, options.OutputFormat == "name", out, "", name, "patched")
+			}
+			return nil
+		}
+
+		count++
+
+		patchedObj, err := api.Scheme.DeepCopy(info.VersionedObject)
+		if err != nil {
+			return err
+		}
+		originalObjJS, err := runtime.Encode(api.Codecs.LegacyCodec(), info.VersionedObject.(runtime.Object))
+		if err != nil {
+			return err
+		}
+		originalPatchedObjJS, err := getPatchedJSON(patchType, originalObjJS, patchBytes, patchedObj.(runtime.Object))
+		if err != nil {
+			return err
+		}
+		targetObj, err := runtime.Decode(api.Codecs.UniversalDecoder(), originalPatchedObjJS)
+		if err != nil {
+			return err
+		}
+		// TODO: if we ever want to go generic, this allows a clean -o yaml without trying to print columns or anything
+		// rawExtension := &runtime.Unknown{
+		// 	Raw: originalPatchedObjJS,
+		// }
+
+		printer, err := f.PrinterForMapping(cmd, mapping, false)
+		if err != nil {
+			return err
+		}
+		if err := printer.PrintObj(targetObj, out); err != nil {
+			return err
+		}
+
 		return nil
 	})
 	if err != nil {
@@ -175,3 +226,24 @@ func RunPatch(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []stri
 	}
 	return nil
 }
+
+func getPatchedJSON(patchType api.PatchType, originalJS, patchJS []byte, obj runtime.Object) ([]byte, error) {
+	switch patchType {
+	case api.JSONPatchType:
+		patchObj, err := jsonpatch.DecodePatch(patchJS)
+		if err != nil {
+			return nil, err
+		}
+		return patchObj.Apply(originalJS)
+
+	case api.MergePatchType:
+		return jsonpatch.MergePatch(originalJS, patchJS)
+
+	case api.StrategicMergePatchType:
+		return strategicpatch.StrategicMergePatchData(originalJS, patchJS, obj)
+
+	default:
+		// only here as a safety net - go-restful filters content-type
+		return nil, fmt.Errorf("unknown Content-Type header for patch: %v", patchType)
+	}
+}