Cache image list with digest key

  fixes #19429

Signed-off-by: stonezdj <daojunz@vmware.com>

src/controller/proxy/controller.go

@@ -183,7 +183,10 @@ func (c *controller) UseLocalManifest(ctx context.Context, art lib.ArtifactInfo,
 	if c.cache == nil {
 		return a != nil && string(desc.Digest) == a.Digest, nil, nil // digest matches
 	}
-
+	// Pass digest to the cache key, digest is more stable than tag, because tag could be updated
+	if len(art.Digest) == 0 {
+		art.Digest = string(desc.Digest)
+	}
 	err = c.cache.Fetch(ctx, manifestListKey(art.Repository, art), &content)
 	if err != nil {
 		if errors.Is(err, cache.ErrNotFound) {
@@ -318,8 +321,8 @@ func getRemoteRepo(art lib.ArtifactInfo) string {
 }
 
 func getReference(art lib.ArtifactInfo) string {
-	if len(art.Tag) > 0 {
-		return art.Tag
+	if len(art.Digest) > 0 {
+		return art.Digest
 	}
-	return art.Digest
+	return art.Tag
 }

src/controller/proxy/manifestcache.go

@@ -73,7 +73,10 @@ func (m *ManifestListCache) CacheContent(ctx context.Context, _ string, man dist
 		log.Errorf("failed to get reference, reference is empty, skip to cache manifest list")
 		return
 	}
-	// some registry will not return the digest in the HEAD request, if no digest returned, cache manifest list content with tag
+	// cache key should contain digest if digest exist
+	if len(art.Digest) == 0 {
+		art.Digest = string(digest.FromBytes(payload))
+	}
 	key := manifestListKey(art.Repository, art)
 	log.Debugf("cache manifest list with key=cache:%v", key)
 	if err := m.cache.Save(ctx, manifestListContentTypeKey(art.Repository, art), contentType, manifestListCacheInterval); err != nil {