[系统运维]Docker Swarm 练习：投票 App

经典示例： Example Voting App 示例投票App

GitHub地址：https://github.com/dockersamples/example-voting-app

网络不好的同学，我已经把源码下载，地址：https://download.csdn.net/download/weixin_48447848/77354937

详细讲解地址请看：Docker Compose 练习：投票 App

Example Voting App 示例投票App

跨多个Docker容器运行的简单分布式应用程序。

Linux 容器 示例

Linux 堆栈使用 Python、Node.js、.NET Core（或可选的 Java），使用 Redis 进行消息传递，使用 Postgres 进行存储。

如果您在 Windows 上使用 Docker Desktop，则可以通过切换到 Linux 容器来运行 Linux 版本，或者运行 Windows 容器版本。

在这个目录下运行：

docker-compose up

该应用程序将在http://localhost:5000运行，结果将在http://localhost:5001。

或者，如果你想在Docker Swarm上运行它，首先确保你有一个 swarm。如果没有，请运行：

docker swarm init

一旦你有了你的 swarm，在这个目录中运行：

docker stack deploy --compose-file docker-stack.yml vote

上手操作 Swarm 多节点集群

前期准备

请看之前文章Docker Swarm 多节点集群，找到一种适合你的搭建多节点的方法。

代码讲解

大部分内容与Docker Compose 练习：投票 App相同，只对Swarm部署的yaml文件讲解。

example-voting-app/docker-stack.yml

deploy：设置部署的参数

• replicas 容器个数
• update_config 更新的参数，几次，间隔时间
• restart_policy 重启的策略

version: "3"
services:

  redis:
    image: redis:alpine
    networks:
      - frontend
    deploy:
      replicas: 1
      update_config:
        parallelism: 2
        delay: 10s
      restart_policy:
        condition: on-failure
  db:
    image: postgres:9.4
    environment:
      POSTGRES_USER: "postgres"
      POSTGRES_PASSWORD: "postgres"
      POSTGRES_HOST_AUTH_METHOD: "trust" # 存在问题，需要添加的字段
    volumes:
      - db-data:/var/lib/postgresql/data
    networks:
      - backend
    deploy:
      placement:
        constraints: [node.role == manager] # db部署到manager节点
  vote:
    image: dockersamples/examplevotingapp_vote:before
    ports:
      - 5000:80
    networks:
      - frontend
    depends_on:
      - redis
    deploy:
      replicas: 2
      update_config:
        parallelism: 2
      restart_policy:
        condition: on-failure
  result:
    image: dockersamples/examplevotingapp_result:before
    ports:
      - 5001:80
    networks:
      - backend
    depends_on:
      - db
    deploy:
      replicas: 1
      update_config:
        parallelism: 2
        delay: 10s
      restart_policy:
        condition: on-failure

  worker:
    image: dockersamples/examplevotingapp_worker
    networks:
      - frontend
      - backend
    depends_on:
      - db
      - redis
    deploy:
      mode: replicated
      replicas: 1
      labels: [APP=VOTING]
      restart_policy:
        condition: on-failure
        delay: 10s
        max_attempts: 3
        window: 120s
      placement:
        constraints: [node.role == manager]

  visualizer:
    image: dockersamples/visualizer:stable
    ports:
      - "8080:8080"
    stop_grace_period: 1m30s
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"
    deploy:
      placement:
        constraints: [node.role == manager]

networks:
  frontend:
  backend:

volumes:
  db-data:

上手操作

新安装的docker是没有启动swarm的，需要初始化

node1节点192.168.0.18为manger管理节点，主要敲命令的：

$ docker swarm init
Error response from daemon: could not choose an IP address to advertise since this system has multiple addresses on different interfaces (172.18.0.4 on eth1 and 192.168.0.18 on eth0) - specify one with --advertise-addr
[node1] (local) root@192.168.0.18 ~
$ docker swarm init --advertise-addr 192.168.0.18
Swarm initialized: current node (y8431tcl51sx54riya31rbvvg) is now a manager.

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

    docker swarm join --token SWMTKN-1-1qrsj4vfuv69hxoizdf21bswxvio4jdjdpvizi42n5g4vicwmv-9rh0c9o6h6iq6mtuge0i3yws2 192.168.0.18:2377

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

[node1] (local) root@192.168.0.18 ~
$ 

node2节点192.168.0.17：

$ docker swarm join --token SWMTKN-1-1qrsj4vfuv69hxoizdf21bswxvio4jdjdpvizi42n5g4vicwmv-9rh0c9o6h6iq6mtuge0i3yws2 192.168.0.18:2377
This node joined a swarm as a worker.
[node2] (local) root@192.168.0.17 ~

node3节点192.168.0.16：

$ docker swarm join --token SWMTKN-1-1qrsj4vfuv69hxoizdf21bswxvio4jdjdpvizi42n5g4vicwmv-9rh0c9o6h6iq6mtuge0i3yws2 192.168.0.18:2377
This node joined a swarm as a worker.
[node3] (local) root@192.168.0.16 ~

创建服务

$ git clone https://github.com/dockersamples/example-voting-app
Cloning into 'example-voting-app'...
remote: Enumerating objects: 971, done.
remote: Total 971 (delta 0), reused 0 (delta 0), pack-reused 971
Receiving objects: 100% (971/971), 982.39 KiB | 9.54 MiB/s, done.
Resolving deltas: 100% (359/359), done.


$ ls
example-voting-app

$ cd example-voting-app/

$ docker stack deploy --compose-file docker-stack.yml vote
Creating network vote_default
Creating network vote_frontend
Creating network vote_backend
Creating service vote_visualizer
Creating service vote_redis
Creating service vote_db
Creating service vote_vote
Creating service vote_result
Creating service vote_worker

查看启动状态

$ docker service ls
ID             NAME              MODE         REPLICAS   IMAGE                                          PORTS
bzdbgncx4aie   vote_db           replicated   1/1        postgres:9.4                                   
midnvgi8pb25   vote_redis        replicated   1/1        redis:alpine                                   
fcyggosob44h   vote_result       replicated   1/1        dockersamples/examplevotingapp_result:before   *:5001->80/tcp
ci0278kb2erd   vote_visualizer   replicated   1/1        dockersamples/visualizer:stable                *:8080->8080/tcp
flh8ecex2q28   vote_vote         replicated   2/2        dockersamples/examplevotingapp_vote:before     *:5000->80/tcp
8f9kvakcrta8   vote_worker       replicated   1/1        dockersamples/examplevotingapp_worker:latest   

查看db数据的日志，发现出现密码错误

docker vervice logs vote_db 
vote_db.1.zg0dbopxmklu@node1    | FATAL:  password authentication failed for user "postgres"
vote_db.1.zg0dbopxmklu@node1    | DETAIL:  Connection matched pg_hba.conf line 95: "host all all all md5

example-voting-app/docker-stack.yml文件需要修改：

  db:
    image: postgres:9.4
    environment:
      POSTGRES_USER: "postgres"
      POSTGRES_PASSWORD: "postgres"
      POSTGRES_HOST_AUTH_METHOD: "trust" # 存在问题，需要添加的字段
    volumes:
      - db-data:/var/lib/postgresql/data

重新启动，直接执行命令，自动更新

$ docker stack  deploy --compose-file docker-stack.yml vote
Updating service vote_worker (id: 8f9kvakcrta8ml0ahbltbyrfu)
Updating service vote_visualizer (id: ci0278kb2erdm55y133pg85nj)
Updating service vote_redis (id: midnvgi8pb25o3oz3ptcawhhz)
Updating service vote_db (id: bzdbgncx4aieb0mgepgoxjl9s)
Updating service vote_vote (id: flh8ecex2q28gcifs53fg2odu)
Updating service vote_result (id: fcyggosob44hs0lzw1q8yzf3q)