feat: support referrers for oci image manifests

registry/handlers/referrers.go

@@ -9,6 +9,7 @@ import (
 	"github.com/distribution/distribution/v3"
 	dcontext "github.com/distribution/distribution/v3/context"
 	"github.com/distribution/distribution/v3/manifest/ociartifact"
+	"github.com/distribution/distribution/v3/manifest/ocischema"
 	"github.com/distribution/distribution/v3/registry/api/errcode"
 	v2 "github.com/distribution/distribution/v3/registry/api/v2"
 	"github.com/distribution/distribution/v3/registry/storage"
@@ -109,29 +110,28 @@ func (h *referrersHandler) generateReferrersList(ctx context.Context, subjectDig
 			if err != nil {
 				return err
 			}
-			artifactManifest, ok := man.(*ociartifact.DeserializedManifest)
-			if !ok {
-				// The PUT handler would guard against this situation. Skip this manifest.
+			switch manifest := man.(type) {
+			case *ocischema.DeserializedManifest:
+				referrer, toAppend, err := generateReferrerFromImage(ctx, blobStatter, referrerDigest, manifest, artifactType)
+				if err != nil {
+					return err
+				}
+				if toAppend {
+					referrers = append(referrers, referrer)
+				}
 				return nil
-			}
-			extractedArtifactType := artifactManifest.ArtifactType
-			// filtering by artifact type or bypass if no artifact type specified
-			if artifactType == "" || extractedArtifactType == artifactType {
-				desc, err := blobStatter.Stat(ctx, referrerDigest)
+			case *ociartifact.DeserializedManifest:
+				referrer, toAppend, err := generateReferrerFromArtifact(ctx, blobStatter, referrerDigest, manifest, artifactType)
 				if err != nil {
 					return err
 				}
-				desc.MediaType, _, _ = man.Payload()
-				artifactDesc := v1.Descriptor{
-					MediaType:    desc.MediaType,
-					Size:         desc.Size,
-					Digest:       desc.Digest,
-					ArtifactType: extractedArtifactType,
-					Annotations:  artifactManifest.Annotations,
+				if toAppend {
+					referrers = append(referrers, referrer)
 				}
-				referrers = append(referrers, artifactDesc)
+				return nil
+			default:
+				return nil
 			}
-			return nil
 		})
 	if err != nil {
 		switch err.(type) {
@@ -190,3 +190,53 @@ func readlink(ctx context.Context, path string, stDriver driver.StorageDriver) (
 
 	return digest.Parse(string(content))
 }
+
+func generateReferrerFromArtifact(ctx context.Context,
+	blobStatter distribution.BlobStatter,
+	referrerDigest digest.Digest,
+	man *ociartifact.DeserializedManifest,
+	artifactType string) (v1.Descriptor, bool, error) {
+	extractedArtifactType := man.ArtifactType
+	// filtering by artifact type or bypass if no artifact type specified
+	if artifactType == "" || extractedArtifactType == artifactType {
+		desc, err := blobStatter.Stat(ctx, referrerDigest)
+		if err != nil {
+			return v1.Descriptor{}, false, err
+		}
+		desc.MediaType, _, _ = man.Payload()
+		artifactDesc := v1.Descriptor{
+			MediaType:    desc.MediaType,
+			Size:         desc.Size,
+			Digest:       desc.Digest,
+			ArtifactType: extractedArtifactType,
+			Annotations:  man.Annotations,
+		}
+		return artifactDesc, true, nil
+	}
+	return v1.Descriptor{}, false, nil
+}
+
+func generateReferrerFromImage(ctx context.Context,
+	blobStatter distribution.BlobStatter,
+	referrerDigest digest.Digest,
+	man *ocischema.DeserializedManifest,
+	configMediaType string) (v1.Descriptor, bool, error) {
+	extractedConfigMediaType := man.Config.MediaType
+	// filtering by artifact type or bypass if no artifact type specified
+	if configMediaType == "" || extractedConfigMediaType == configMediaType {
+		desc, err := blobStatter.Stat(ctx, referrerDigest)
+		if err != nil {
+			return v1.Descriptor{}, false, err
+		}
+		desc.MediaType, _, _ = man.Payload()
+		imageDesc := v1.Descriptor{
+			MediaType:    desc.MediaType,
+			Size:         desc.Size,
+			Digest:       desc.Digest,
+			ArtifactType: extractedConfigMediaType,
+			Annotations:  man.Annotations,
+		}
+		return imageDesc, true, nil
+	}
+	return v1.Descriptor{}, false, nil
+}