https://blog.toright.com/posts/5598/%e7%94%a8-docker-swarm-%e9%83%a8%e7%bd%b2%e4%bd%a0%e7%9a%84%e9%9b%b2%e6%9c%8d%e5%8b%99-%e5%af%a6%e4%bd%9c%e7%af%87
用 Docker Swarm 部署你的雲服務 (實作篇)