fill-in some basic configuration parameters if config file is not set

def set_defaults(config, cluster_name):
    """fill-in some basic configuration parameters if config file is not set """
    config['postgresql'].setdefault('name', cluster_name)
    config['postgresql'].setdefault('scope', cluster_name)
    config['postgresql'].setdefault('listen', '127.0.0.1')
    config['postgresql']['authentication'] = {'replication': None}
    config['restapi']['listen'] = ':' in config['restapi']['listen'] and config['restapi']['listen'] or '127.0.0.1:8008'