prow/pod-utils/gcs/upload.go
func DataUploadWithMetadata(src io.Reader, metadata map[string]string) UploadFunc {
	return func(obj *storage.ObjectHandle) error {
		writer := obj.NewWriter(context.Background())
		writer.Metadata = metadata
		_, copyErr := io.Copy(writer, src)
		closeErr := writer.Close()

		return errorutil.NewAggregate(copyErr, closeErr)
	}
}
func DataUploadWithMetadata(src io.Reader, metadata map[string]string) UploadFunc {
	return func(obj *storage.ObjectHandle) error {
		writer := obj.NewWriter(context.Background())
		writer.Metadata = metadata
		_, copyErr := io.Copy(writer, src)
		closeErr := writer.Close()

		return errorutil.NewAggregate(copyErr, closeErr)
	}
}
// DataUploadWithMetadata returns an UploadFunc which copies all
// data from src reader into GCS and also sets the provided metadata
// fields onto the object.