mysqlops.py 文件源码

def swap_master_and_slave(instance, dry_run):
    """ Swap a master and slave in zk. Warning: this does not sanity checks
        and does nothing more than update zk. YOU HAVE BEEN WARNED!

    Args:
    instance - An instance in the replica set. This function will figure
               everything else out.
    dry_run - If set, do not modify configuration.
    """
    zk_local = MysqlZookeeper()
    kazoo_client = get_kazoo_client()
    if not kazoo_client:
        raise Exception('Could not get a zk connection')

    log.info('Instance is {inst}'.format(inst=instance))
    (replica_set, version) = zk_local.get_replica_set_from_instance(instance)
    log.info('Detected replica_set as '
             '{replica_set}'.format(replica_set=replica_set))
    (zk_node, parsed_data,
     version) = get_zk_node_for_replica_set(kazoo_client, replica_set)
    log.info('Replica set {replica_set} is held in zk_node '
             '{zk_node}'.format(
                 zk_node=zk_node, replica_set=replica_set))

    log.info('Existing config:')
    log.info(pprint.pformat(remove_auth(parsed_data[replica_set])))
    new_data = copy.deepcopy(parsed_data)
    new_data[replica_set][REPLICA_ROLE_MASTER] = \
        parsed_data[replica_set][REPLICA_ROLE_SLAVE]
    new_data[replica_set][REPLICA_ROLE_SLAVE] = \
        parsed_data[replica_set][REPLICA_ROLE_MASTER]

    log.info('New config:')
    log.info(pprint.pformat(remove_auth(new_data[replica_set])))

    if new_data == parsed_data:
        raise Exception('No change would be made to zk, '
                        'will not write new config')
    elif dry_run:
        log.info('dry_run is set, therefore not modifying zk')
    else:
        log.info('Pushing new configuration for '
                 '{replica_set}:'.format(replica_set=replica_set))
        kazoo_client.set(zk_node, simplejson.dumps(new_data), version)