Allow overriding the manifestdescriptor when pushing

pkg/oras/push.go

@@ -83,24 +83,29 @@ func pack(provider content.Provider, descriptors []ocispec.Descriptor, opts *pus
 	}
 
 	// Manifest
-	manifest := ocispec.Manifest{
-		Versioned: specs.Versioned{
-			SchemaVersion: 2, // historical value. does not pertain to OCI or docker version
-		},
-		Config:      config,
-		Layers:      descriptors,
-		Annotations: opts.manifestAnnotations,
-	}
-	manifestBytes, err := json.Marshal(manifest)
-	if err != nil {
-		return ocispec.Descriptor{}, nil, err
-	}
-	manifestDescriptor := ocispec.Descriptor{
-		MediaType: ocispec.MediaTypeImageManifest,
-		Digest:    digest.FromBytes(manifestBytes),
-		Size:      int64(len(manifestBytes)),
+	var manifestDescriptor ocispec.Descriptor
+	if opts.manifest == nil {
+		manifest := ocispec.Manifest{
+			Versioned: specs.Versioned{
+				SchemaVersion: 2, // historical value. does not pertain to OCI or docker version
+			},
+			Config:      config,
+			Layers:      descriptors,
+			Annotations: opts.manifestAnnotations,
+		}
+		manifestBytes, err := json.Marshal(manifest)
+		if err != nil {
+			return ocispec.Descriptor{}, nil, err
+		}
+		manifestDescriptor = ocispec.Descriptor{
+			MediaType: ocispec.MediaTypeImageManifest,
+			Digest:    digest.FromBytes(manifestBytes),
+			Size:      int64(len(manifestBytes)),
+		}
+		store.Set(manifestDescriptor, manifestBytes)
+	} else {
+		manifestDescriptor = *opts.manifest
 	}
-	store.Set(manifestDescriptor, manifestBytes)
 
 	return manifestDescriptor, store, nil
 }

pkg/oras/push_opts.go

@@ -15,6 +15,7 @@ type pushOpts struct {
 	config              *ocispec.Descriptor
 	configMediaType     string
 	configAnnotations   map[string]string
+	manifest            *ocispec.Descriptor
 	manifestAnnotations map[string]string
 	validateName        func(desc ocispec.Descriptor) error
 	baseHandlers        []images.Handler
@@ -53,6 +54,14 @@ func WithConfigAnnotations(annotations map[string]string) PushOpt {
 	}
 }
 
+// WithManifest overrides the manifest
+func WithManifest(manifest ocispec.Descriptor) PushOpt {
+	return func(o *pushOpts) error {
+		o.manifest = &manifest
+		return nil
+	}
+}
+
 // WithManifestAnnotations overrides the manifest annotations
 func WithManifestAnnotations(annotations map[string]string) PushOpt {
 	return func(o *pushOpts) error {