feat(crane): allow setting the repository to push by digest (#1323)

* feat(crane): allow setting the repository to push by digest

Signed-off-by: Markus Lippert <[email protected]>

* apply suggestions

Signed-off-by: Markus Lippert <[email protected]>

* Update cmd/crane/cmd/mutate.go

Co-authored-by: Jason Hall <[email protected]>

* update docs

Signed-off-by: Markus Lippert <[email protected]>

Co-authored-by: Jason Hall <[email protected]>

Author: lippertmarkus

Diff for: cmd/crane/cmd/mutate.go

@@ -35,6 +35,7 @@ func NewCmdMutate(options *[]crane.Option) *cobra.Command {
 	var newLayers []string
 	var outFile string
 	var newRef string
+	var newRepo string
 	var user string
 
 	mutateCmd := &cobra.Command{
@@ -55,6 +56,10 @@ func NewCmdMutate(options *[]crane.Option) *cobra.Command {
 				}
 			}
 
+			if newRepo != "" && newRef != "" {
+				return errors.New("repository can't be set when a tag is specified")
+			}
+
 			img, err := crane.Pull(ref, *options...)
 			if err != nil {
 				return fmt.Errorf("pulling %s: %w", ref, err)
@@ -121,7 +126,9 @@ func NewCmdMutate(options *[]crane.Option) *cobra.Command {
 			// If that ref was provided by digest (e.g., output from
 			// another crane command), then strip that and push the
 			// mutated image by digest instead.
-			if newRef == "" {
+			if newRepo != "" {
+				newRef = newRepo
+			} else if newRef == "" {
 				newRef = ref
 			}
 			digest, err := img.Digest()
@@ -137,7 +144,7 @@ func NewCmdMutate(options *[]crane.Option) *cobra.Command {
 				if err != nil {
 					return fmt.Errorf("parsing %s: %w", newRef, err)
 				}
-				if _, ok := r.(name.Digest); ok {
+				if _, ok := r.(name.Digest); ok || newRepo != "" {
 					newRef = r.Context().Digest(digest.String()).String()
 				}
 				if err := crane.Push(img, newRef, *options...); err != nil {
@@ -153,7 +160,8 @@ func NewCmdMutate(options *[]crane.Option) *cobra.Command {
 	mutateCmd.Flags().StringToStringVarP(&envVars, "env", "e", nil, "New envvar to add")
 	mutateCmd.Flags().StringSliceVar(&entrypoint, "entrypoint", nil, "New entrypoint to set")
 	mutateCmd.Flags().StringSliceVar(&cmd, "cmd", nil, "New cmd to set")
-	mutateCmd.Flags().StringVarP(&newRef, "tag", "t", "", "New tag to apply to mutated image. If not provided, push by digest to the original image repository.")
+	mutateCmd.Flags().StringVar(&newRepo, "repo", "", "Repository to push the mutated image to. If provided, push by digest to this repository.")
+	mutateCmd.Flags().StringVarP(&newRef, "tag", "t", "", "New tag reference to apply to mutated image. If not provided, push by digest to the original image repository.")
 	mutateCmd.Flags().StringVarP(&outFile, "output", "o", "", "Path to new tarball of resulting image")
 	mutateCmd.Flags().StringSliceVar(&newLayers, "append", []string{}, "Path to tarball to append to image")
 	mutateCmd.Flags().StringVarP(&user, "user", "u", "", "New user to set")