Allow mutate.Annotations to annotate an Image or ImageIndex

cmd/crane/cmd/mutate.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/mutate"
 	"github.com/spf13/cobra"
 )
@@ -91,7 +92,7 @@ func NewCmdMutate(options *[]crane.Option) *cobra.Command {
 				log.Fatalf("mutating config: %v", err)
 			}
 
-			img = mutate.Annotations(img, annotations)
+			img = mutate.Annotations(img, annotations).(v1.Image)
 
 			// If the new ref isn't provided, write over the original image.
 			// If that ref was provided by digest (e.g., output from

pkg/v1/mutate/index.go

@@ -61,12 +61,13 @@ type index struct {
 	// remove is removed before adds
 	remove match.Matcher
 
-	computed  bool
-	manifest  *v1.IndexManifest
-	mediaType *types.MediaType
-	imageMap  map[v1.Hash]v1.Image
-	indexMap  map[v1.Hash]v1.ImageIndex
-	layerMap  map[v1.Hash]v1.Layer
+	computed    bool
+	manifest    *v1.IndexManifest
+	annotations map[string]string
+	mediaType   *types.MediaType
+	imageMap    map[v1.Hash]v1.Image
+	indexMap    map[v1.Hash]v1.ImageIndex
+	layerMap    map[v1.Hash]v1.Layer
 }
 
 var _ v1.ImageIndex = (*index)(nil)
@@ -137,6 +138,15 @@ func (i *index) compute() error {
 		}
 	}
 
+	if i.annotations != nil {
+		if manifest.Annotations == nil {
+			manifest.Annotations = map[string]string{}
+		}
+		for k, v := range i.annotations {
+			manifest.Annotations[k] = v
+		}
+	}
+
 	i.manifest = manifest
 	i.computed = true
 	return nil

pkg/v1/mutate/mutate.go

@@ -28,6 +28,7 @@ import (
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/empty"
 	"github.com/google/go-containerregistry/pkg/v1/match"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
 	"github.com/google/go-containerregistry/pkg/v1/types"
 )
@@ -113,12 +114,42 @@ func Config(base v1.Image, cfg v1.Config) (v1.Image, error) {
 	return ConfigFile(base, cf)
 }
 
-// Annotations mutates the provided v1.Image to have the provided annotations
-func Annotations(base v1.Image, annotations map[string]string) v1.Image {
-	return &image{
-		base:        base,
-		annotations: annotations,
+// Annotateable represents a manifest that can carry annotations.
+type Annotateable interface {
+	partial.WithRawManifest
+}
+
+// Annotations mutates the annotations on an annotateable image or index manifest.
+//
+// The annotateable input is expected to be a v1.Image or v1.ImageIndex, and
+// returns the same type. You can type-assert the result like so:
+//
+//     img := Annotations(empty.Image, map[string]string{
+//         "foo": "bar",
+//     }).(v1.Image)
+//
+// Or for an index:
+//
+//     idx := Annotations(empty.Index, map[string]string{
+//         "foo": "bar",
+//     }).(v1.ImageIndex)
+//
+// If the input Annotateable is not an Image or ImageIndex, it is simply
+// returned without modification.
+func Annotations(f Annotateable, anns map[string]string) Annotateable {
+	if img, ok := f.(v1.Image); ok {
+		return &image{
+			base:        img,
+			annotations: anns,
+		}
+	}
+	if idx, ok := f.(v1.ImageIndex); ok {
+		return &index{
+			base:        idx,
+			annotations: anns,
+		}
 	}
+	return f
 }
 
 // ConfigFile mutates the provided v1.Image to have the provided v1.ConfigFile

pkg/v1/mutate/mutate_test.go

@@ -273,7 +273,7 @@ func TestAnnotations(t *testing.T) {
 		"im.the.first.annotation": "hello world",
 	}
 
-	result := mutate.Annotations(source, newAnnotations)
+	result := mutate.Annotations(source, newAnnotations).(v1.Image)
 
 	if configDigestsAreEqual(t, source, result) {
 		t.Errorf("mutating the manifest annotations MUST mutate the config digest")