fix: ignore error of manifest tag path not found in gc (#4331)

registry/storage/garbagecollect.go

@@ -73,7 +73,8 @@ func MarkAndSweep(ctx context.Context, storageDriver driver.StorageDriver, regis
 					// which means that we need check (and delete) those references when deleting manifest
 					allTags, err := repository.Tags(ctx).All(ctx)
 					if err != nil {
-						if _, ok := err.(distribution.ErrManifestUnknownRevision); !ok {
+						if _, ok := err.(distribution.ErrRepositoryUnknown); ok {
+							emit("manifest tags path of repository %s does not exist", repoName)
 							return nil
 						}
 						return fmt.Errorf("failed to retrieve tags %v", err)

registry/storage/garbagecollect_test.go

@@ -416,6 +416,39 @@ func TestDeleteManifestIndexIfTagNotFound(t *testing.T) {
 	}
 }
 
+func TestGCWithUnknownRepository(t *testing.T) {
+	ctx := dcontext.Background()
+	d := inmemory.New()
+
+	registry := createRegistry(t, d)
+	repo := makeRepository(t, registry, "nonexistentrepo")
+	image := uploadRandomSchema2Image(t, repo)
+
+	err := repo.Tags(ctx).Tag(ctx, "image", distribution.Descriptor{Digest: image.manifestDigest})
+	if err != nil {
+		t.Fatalf("Failed to tag descriptor: %v", err)
+	}
+
+	// Simulate a missing _manifests/tags directory
+	manifestTagsPath, err := pathFor(manifestTagsPathSpec{"nonexistentrepo"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = d.Delete(ctx, manifestTagsPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = MarkAndSweep(dcontext.Background(), d, registry, GCOpts{
+		DryRun:         false,
+		RemoveUntagged: true,
+	})
+	if err != nil {
+		t.Fatalf("got error: %v, expected nil", err)
+	}
+}
+
 func TestGCWithMissingManifests(t *testing.T) {
 	ctx := dcontext.Background()
 	d := inmemory.New()