Add --set-base-image-annotations flag to crane append (#1098)

* Add --annotate flag to crane append

This flag instructs crane append to annotate the resulting image with
information about the base image (name and current digest). This flag is
false by default.

* update codegen

* change flag name, don't set base name if it's a digest

* use ref.Name() which canonicalizes e.g., ubuntu -> index.docker.io/library/ubuntu

* don't set empty annotation

cmd/crane/cmd/append.go

@@ -22,13 +22,16 @@ import (
 	"github.com/google/go-containerregistry/pkg/name"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	specsv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/spf13/cobra"
 )
 
 // NewCmdAppend creates a new cobra.Command for the append subcommand.
 func NewCmdAppend(options *[]crane.Option) *cobra.Command {
 	var baseRef, newTag, outFile string
 	var newLayers []string
+	var annotate bool
 
 	appendCmd := &cobra.Command{
 		Use:   "append",
@@ -53,6 +56,25 @@ func NewCmdAppend(options *[]crane.Option) *cobra.Command {
 				return fmt.Errorf("appending %v: %v", newLayers, err)
 			}
 
+			if baseRef != "" && annotate {
+				ref, err := name.ParseReference(baseRef)
+				if err != nil {
+					return fmt.Errorf("parsing ref %q: %v", baseRef, err)
+				}
+
+				baseDigest, err := base.Digest()
+				if err != nil {
+					return err
+				}
+				anns := map[string]string{
+					specsv1.AnnotationBaseImageDigest: baseDigest.String(),
+				}
+				if _, ok := ref.(name.Tag); ok {
+					anns[specsv1.AnnotationBaseImageName] = ref.Name()
+				}
+				img = mutate.Annotations(img, anns).(v1.Image)
+			}
+
 			if outFile != "" {
 				if err := crane.Save(img, newTag, outFile); err != nil {
 					return fmt.Errorf("writing output %q: %v", outFile, err)
@@ -78,6 +100,7 @@ func NewCmdAppend(options *[]crane.Option) *cobra.Command {
 	appendCmd.Flags().StringVarP(&newTag, "new_tag", "t", "", "Tag to apply to resulting image")
 	appendCmd.Flags().StringSliceVarP(&newLayers, "new_layer", "f", []string{}, "Path to tarball to append to image")
 	appendCmd.Flags().StringVarP(&outFile, "output", "o", "", "Path to new tarball of resulting image")
+	appendCmd.Flags().BoolVar(&annotate, "set-base-image-annotations", false, "If true, annotate the resulting image as being based on the base image")
 
 	appendCmd.MarkFlagRequired("new_tag")
 	appendCmd.MarkFlagRequired("new_layer")

go.mod

@@ -18,7 +18,7 @@ require (
 	github.com/kr/text v0.2.0 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e // indirect
-	github.com/opencontainers/image-spec v1.0.1
+	github.com/opencontainers/image-spec v1.0.2-0.20210730191737-8e42a01fb1b7
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/sirupsen/logrus v1.8.1 // indirect
 	github.com/spf13/cobra v1.2.1

vendor/modules.txt

@@ -96,7 +96,7 @@ github.com/klauspost/compress/zstd/internal/xxhash
 ## explicit
 # github.com/opencontainers/go-digest v1.0.0
 github.com/opencontainers/go-digest
-# github.com/opencontainers/image-spec v1.0.1
+# github.com/opencontainers/image-spec v1.0.2-0.20210730191737-8e42a01fb1b7
 ## explicit
 github.com/opencontainers/image-spec/specs-go
 github.com/opencontainers/image-spec/specs-go/v1