fix(storage): copy metadata when using Copier with grpc (#12919)

BrennaEpp · web-flow · commit 57a2e804f690 · 2025-10-14T13:32:15.000-04:00
We need to not set `destination` on the request unless the user
specifies attrs. Since the struct is not a pointer, we have to check if
it is empty to determine if it has not been set.
diff --git a/storage/grpc_client.go b/storage/grpc_client.go
@@ -952,14 +952,24 @@ func (c *grpcStorageClient) ComposeObject(ctx context.Context, req *composeObjec
 }
 func (c *grpcStorageClient) RewriteObject(ctx context.Context, req *rewriteObjectRequest, opts ...storageOption) (*rewriteObjectResponse, error) {
 	s := callSettings(c.settings, opts...)
-	obj := req.dstObject.attrs.toProtoObject("")
+
+	var dst *storagepb.Object
+	// If the destination object attributes are not set, do not include them
+	// in the request. This indicates that the object attributes should be
+	// copied from the source object.
+	if req.dstObject.attrs.isZero() {
+		dst = nil
+	} else {
+		dst = req.dstObject.attrs.toProtoObject("")
+	}
+
 	call := &storagepb.RewriteObjectRequest{
 		SourceBucket:              bucketResourceName(globalProjectAlias, req.srcObject.bucket),
 		SourceObject:              req.srcObject.name,
 		RewriteToken:              req.token,
 		DestinationBucket:         bucketResourceName(globalProjectAlias, req.dstObject.bucket),
 		DestinationName:           req.dstObject.name,
-		Destination:               obj,
+		Destination:               dst,
 		DestinationKmsKey:         req.dstObject.keyName,
 		DestinationPredefinedAcl:  req.predefinedACL,
 		CommonObjectRequestParams: toProtoCommonObjectRequestParams(req.dstObject.encryptionKey),
diff --git a/storage/integration_test.go b/storage/integration_test.go
@@ -2406,7 +2406,7 @@ func TestIntegration_Copy(t *testing.T) {
 		})
 
 		// Create new bucket
-		if err := bucketInDifferentRegion.Create(ctx, testutil.ProjID(), &BucketAttrs{Location: "NORTHAMERICA-NORTHEAST2"}); err != nil {
+		if err := bucketInDifferentRegion.Create(ctx, testutil.ProjID(), &BucketAttrs{Location: "US-EAST1"}); err != nil {
 			t.Fatalf("bucket.Create: %v", err)
 		}
 		t.Cleanup(func() {
@@ -2434,6 +2434,14 @@ func TestIntegration_Copy(t *testing.T) {
 			h.mustDeleteObject(obj)
 		})
 
+		// Set metadata on the source object to check if it's copied.
+		if _, err := obj.Update(ctx, ObjectAttrsToUpdate{
+			ContentLanguage:    "en",
+			ContentDisposition: "inline",
+		}); err != nil {
+			t.Fatalf("obj.Update: %v", err)
+		}
+
 		attrs, err := obj.Attrs(ctx)
 		if err != nil {
 			t.Fatalf("obj.Attrs: %v", err)
@@ -2518,6 +2526,14 @@ func TestIntegration_Copy(t *testing.T) {
 					if attrs.ContentEncoding != test.copierAttrs.contentEncoding {
 						t.Errorf("unexpected ContentEncoding; got: %s, want: %s", attrs.ContentEncoding, test.copierAttrs.contentEncoding)
 					}
+				} else {
+					// Check that metadata is copied when no destination attributes are provided.
+					if attrs.ContentLanguage != "en" {
+						t.Errorf("unexpected ContentLanguage; got: %s, want: en", attrs.ContentLanguage)
+					}
+					if attrs.ContentDisposition != "inline" {
+						t.Errorf("unexpected ContentDisposition; got: %s, want: inline", attrs.ContentDisposition)
+					}
 				}
 
 				// Check the copied contents
diff --git a/storage/storage.go b/storage/storage.go
@@ -1672,6 +1672,12 @@ type ObjectAttrs struct {
 	HardDeleteTime time.Time
 }
 
+// isZero reports whether the ObjectAttrs struct is empty (i.e. all the
+// fields are their zero value).
+func (o *ObjectAttrs) isZero() bool {
+	return reflect.DeepEqual(o, &ObjectAttrs{})
+}
+
 // ObjectRetention contains the retention configuration for this object.
 type ObjectRetention struct {
 	// Mode is the retention policy's mode on this object. Valid values are
