def _get_gae_credentials():
    """Gets Google App Engine App Identity credentials and project ID."""
    # While this library is normally bundled with app_engine, there are
    # some cases where it's not available, so we tolerate ImportError.
    try:
        import google.auth.app_engine as app_engine
    except ImportError:
        return None, None

    try:
        credentials = app_engine.Credentials()
        project_id = app_engine.get_project_id()
        return credentials, project_id
    except EnvironmentError:
        return None, None
Gets Google App Engine App Identity credentials and project ID.