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Docker Swarm

Docker Swarm 是 Docker 官方出的容器調度系統

Setup

Docker Machine + VirtualBox

先建機器

docker-machine create -d virtualbox node1
docker-machine create -d virtualbox node2
docker-machine create -d virtualbox node3

接著選定一台當做 Manager，比方說是 node1。接著切換到 node1 上初始化 Swarm

$ eval $(docker-machine env node1)
$ docker swarm init --advertise-addr 192.168.99.100  # 因為 VirtualBox 預設會起兩個網路介面
Swarm initialized: current node (8o4fxwxu8e4zqhxn4vco7rguj) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join \
    --token SWMTKN-1-3dmqscpgn6jwxk5o7zlmum5i2655um6bv1lgmtcztp48h4fh4n-bgmembhgaok4lhjzo2adxwsho \
    192.168.99.100:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

上面會提示 Worker 要下的指令，接著切換到 node2 node3 下指令

$ eval $(docker-machine env node2)
$ docker swarm join --token SWMTKN-1-3dmqscpgn6jwxk5o7zlmum5i2655um6bv1lgmtcztp48h4fh4n-bgmembhgaok4lhjzo2adxwsho 192.168.99.100:2377
This node joined a swarm as a worker.
$ eval $(docker-machine env node3)
$ docker swarm join --token SWMTKN-1-3dmqscpgn6jwxk5o7zlmum5i2655um6bv1lgmtcztp48h4fh4n-bgmembhgaok4lhjzo2adxwsho 192.168.99.100:2377
This node joined a swarm as a worker.

到此，Swarm 的環境已算初始化完成了，接著到 Manager 開始啟動 Service

$ docker service create --name web -p 8000:80 nginx:alpine
4r0x9rts2adklf3tt9816av50

Scaling

$ docker service scale web=30
web scaled to 30

Update

$ docker service update --image nginx:latest web
web

在操作上很像是在單機操作，但這些操作都會同步到所有 worker。

References

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