def bdev_rbd_register_cluster(client, name, user=None, config_param=None, config_file=None, key_file=None):
    """Create a Rados Cluster object of the Ceph RBD backend.

    Args:
        name: name of Rados Cluster
        user: Ceph user name (optional)
        config_param: map of config keys to values (optional)
        config_file: file path of Ceph configuration file (optional)
        key_file: file path of Ceph key file (optional)

    Returns:
        Name of registered Rados Cluster object.
    """
    params = {'name': name}

    if user is not None:
        params['user_id'] = user
    if config_param is not None:
        params['config_param'] = config_param
    if config_file is not None:
        params['config_file'] = config_file
    if key_file is not None:
        params['key_file'] = key_file

    return client.call('bdev_rbd_register_cluster', params)