Citus 官方docker demo 中membership-manager原理简单说明

def docker_checker():

    client = docker.DockerClient(base_url='unix:///var/run/docker.sock')

    actions = {'health_status: healthy': add_worker, 'destroy': remove_worker}

​

    # creates the necessary connection to make the sql calls if the master is ready

    conn = connect_to_master()

​

    # introspect the compose project used by this citus cluster

    my_hostname = environ['HOSTNAME']

    this_container = client.containers.get(my_hostname)

    compose_project = this_container.labels['com.docker.compose.project']

​

    # we only care about worker container health/destroy events from this cluster

    print("found compose project: %s" % compose_project, file=stderr)

    filters = {'event': list(actions),

               'label': ["com.docker.compose.project=%s" % compose_project,

                         "com.citusdata.role=Worker"],

               'type': 'container'}

​

​

    # touch a file to signal we're healthy, then consume events

    print('listening for events...', file=stderr)

    open('/manager-ready', 'a').close()

    for event in client.events(decode=True, filters=filters):

        worker_name = event['Actor']['Attributes']['name']

        status = event['status']