Preserve the full source reference in MountableLayer

Mounting is just one way to take advantage of this information, so preserve as much information as we can to support other potential uses of this information.

Related: google#205

pkg/v1/remote/image.go

@@ -61,8 +61,8 @@ func Image(ref name.Reference, auth authn.Authenticator, t http.RoundTripper) (v
 	// Wrap the v1.Layers returned by this v1.Image in a hint for downstream
 	// remote.Write calls to facilitate cross-repo "mounting".
 	return &mountableImage{
-		Image:      img,
-		Repository: ref.Context(),
+		Image:     img,
+		Reference: ref,
 	}, nil
 }
 

pkg/v1/remote/mount.go

@@ -24,7 +24,7 @@ import (
 type MountableLayer struct {
 	v1.Layer
 
-	Repository name.Repository
+	Reference name.Reference
 }
 
 // mountableImage wraps the v1.Layer references returned by the embedded v1.Image
@@ -33,7 +33,7 @@ type MountableLayer struct {
 type mountableImage struct {
 	v1.Image
 
-	Repository name.Repository
+	Reference name.Reference
 }
 
 // Layers implements v1.Image
@@ -45,8 +45,8 @@ func (mi *mountableImage) Layers() ([]v1.Layer, error) {
 	mls := make([]v1.Layer, 0, len(ls))
 	for _, l := range ls {
 		mls = append(mls, &MountableLayer{
-			Layer:      l,
-			Repository: mi.Repository,
+			Layer:     l,
+			Reference: mi.Reference,
 		})
 	}
 	return mls, nil
@@ -59,8 +59,8 @@ func (mi *mountableImage) LayerByDigest(d v1.Hash) (v1.Layer, error) {
 		return nil, err
 	}
 	return &MountableLayer{
-		Layer:      l,
-		Repository: mi.Repository,
+		Layer:     l,
+		Reference: mi.Reference,
 	}, nil
 }
 
@@ -71,7 +71,7 @@ func (mi *mountableImage) LayerByDiffID(d v1.Hash) (v1.Layer, error) {
 		return nil, err
 	}
 	return &MountableLayer{
-		Layer:      l,
-		Repository: mi.Repository,
+		Layer:     l,
+		Reference: mi.Reference,
 	}, nil
 }

pkg/v1/remote/write.go

@@ -45,7 +45,7 @@ func Write(ref name.Reference, img v1.Image, auth authn.Authenticator, t http.Ro
 	scopes := []string{ref.Scope(transport.PushScope)}
 	for _, l := range ls {
 		if ml, ok := l.(*MountableLayer); ok {
-			scopes = append(scopes, ml.Repository.Scope(transport.PullScope))
+			scopes = append(scopes, ml.Reference.Context().Scope(transport.PullScope))
 		}
 	}
 
@@ -145,7 +145,7 @@ func (w *writer) initiateUpload(h v1.Hash) (location string, mounted bool, err e
 	// if "mount" is specified, even if no "from" sources are specified.  If this turns out
 	// to not be broadly applicable then we should replace mounts without "from"s with a HEAD.
 	if ml, ok := l.(*MountableLayer); ok {
-		uv["from"] = []string{ml.Repository.RepositoryStr()}
+		uv["from"] = []string{ml.Reference.Context().RepositoryStr()}
 	}
 	u.RawQuery = uv.Encode()
 

pkg/v1/remote/write_test.go

@@ -266,8 +266,8 @@ func TestInitiateUploadMountsWithMount(t *testing.T) {
 	}.Encode()
 
 	img = &mountableImage{
-		Image:      img,
-		Repository: mustNewTag(t, fmt.Sprintf("gcr.io/%s", expectedMountRepo)).Repository,
+		Image:     img,
+		Reference: mustNewTag(t, fmt.Sprintf("gcr.io/%s", expectedMountRepo)),
 	}
 
 	w, closer, err := setupWriter(expectedRepo, img, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {