请先看上一篇文章：https://www.yuque.com/tangwx/linux/xrn8oo

    1. version: '3'
    2. services:
    3.   api:
    4.     image: 10.211.55.103:5000/swarm/swarm-api:1.0-SNAPSHOT
    5.     ports:
    6.       - "8123:8123"
    7.     stop_grace_period: 10s
    8.     deploy:
    9.       mode: replicated
    10.       replicas: 3
    11.     networks:
    12.       - uber-over 
    14.   client:
    15.     image: 10.211.55.103:5000/swarm/swarm-client:1.0-SNAPSHOT
    16.     ports:
    17.       - "8124:8124"
    18.     stop_grace_period: 10s
    19.     deploy:
    20.       mode: replicated
    21.       replicas: 3
    22.     networks:
    23.       - uber-over  
    25. networks:
    26.   uber-over:
    27.     external: true

    注意网络被标记为外部：

    networks:
    uber-over: external: true

    uber-over 网络需要先行创建： docker network create -d overlay uber-over

    此时运行docker stack deploy -c docker-mh.yml mh 命令将不再创建 uber-over 网络

    同理，在其他stack中也指定相同的外部网络，那么这些stack便能互通了。