^(?:(?:[a-z0-9\.\-]+(?::\d+)?/)?[a-z0-9]+(?:[._-][a-z0-9]+)*)(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9_][a-zA-Z0-9\._\-]{0,127})?(?:@sha256:[a-f0-9]{64})?$