use interface

Author: imjasonh

pkg/v1/mutate/image.go

@@ -39,6 +39,13 @@ type image struct {
 	digestMap       map[v1.Hash]v1.Layer
 }
 
+func (i *image) ETag() string {
+	if e, ok := i.base.(partial.WithETag); ok {
+		return e.ETag()
+	}
+	return ""
+}
+
 var _ v1.Image = (*image)(nil)
 
 func (i *image) MediaType() (types.MediaType, error) {

pkg/v1/partial/with.go

@@ -25,6 +25,16 @@ import (
 	"github.com/google/go-containerregistry/pkg/v1/types"
 )
 
+// WithETag defines the subset of manifest types that can expose an ETag
+// returned by a registry server.
+//
+// If a manifest provides an ETag using this method, it will be used when
+// pushing updates, to prevent race conditions.
+type WithETag interface {
+	// ETag returns the ETag returned by remote registry implementations.
+	ETag() string
+}
+
 // WithRawConfigFile defines the subset of v1.Image used by these helper methods
 type WithRawConfigFile interface {
 	// RawConfigFile returns the serialized bytes of this image's config file.

pkg/v1/remote/image.go

@@ -60,6 +60,8 @@ func Image(ref name.Reference, options ...Option) (v1.Image, error) {
 	return desc.Image()
 }
 
+func (r *remoteImage) ETag() string { return r.etag }
+
 func (r *remoteImage) MediaType() (types.MediaType, error) {
 	if string(r.mediaType) != "" {
 		return r.mediaType, nil

pkg/v1/remote/index.go

@@ -51,6 +51,8 @@ func Index(ref name.Reference, options ...Option) (v1.ImageIndex, error) {
 	return desc.ImageIndex()
 }
 
+func (r *remoteIndex) ETag() string { return r.etag }
+
 func (r *remoteIndex) MediaType() (types.MediaType, error) {
 	if string(r.mediaType) != "" {
 		return r.mediaType, nil

pkg/v1/remote/write.go

@@ -612,11 +612,8 @@ func (w *writer) commitManifest(ctx context.Context, t Taggable, ref name.Refere
 		}
 		req.Header.Set("Content-Type", string(desc.MediaType))
 
-		if ri, ok := t.(*remoteImage); ok && ri.etag != "" {
-			req.Header.Set("If-Match", ri.etag)
-		}
-		if ri, ok := t.(*remoteIndex); ok && ri.etag != "" {
-			req.Header.Set("If-Match", ri.etag)
+		if e, ok := t.(partial.WithETag); ok && e.ETag() != "" {
+			req.Header.Set("If-Match", e.ETag())
 		}
 
 		resp, err := w.client.Do(req.WithContext(ctx))