docker-compose

docker-compose 是docker官方的单机编排工具,适用于多个容器配合工作的场景,Compose项目由Python编写﹐实际上调用了Docker服务提供的API来对容器进管理

[INFO]

Compose 中有两个重要的概念︰

服务(service):一个应用的容器﹐实际上可以包括若干运行相同镜像的容器实例。
项目(project)∶由一组关联的应用容器组成的一个完整业务单元﹐在docker-compose.yml文件中定义。

Compose的默认管理对象是项目﹐通过子命令对项目中的一组容器进行便捷地生命周期管理。

安装docker-compose

方法一：通过仓库安装
pip install docker-compose
yum install docker-compose
方法二：二进制安装
方法三：在容器中运行
docker-compose version

我们来熟悉下docker-compose.yml 的基本格式

wordpress:
  images: wiki:latest
  name: wordpress
  restart: always
  ports: "80:80"

mysql:
  images: 1209233066/mysql:v8.1
  volumes: /var/lib/mysql/:/var/lib/mysql/
  restart: always
  env: MYSQL_ROOT_PASSWORD=123
  name: mysql
  net: "container:wordpress"

接下来一步步构建自己的docker-compese.yml项目

1. Version声明项目使用的版本，不声明也不会出现错误

   version: "3"
   

2. services每一个需要启动的容器都是一个服务

   version: "3"
   services:
     python：
       image: python
   

3. command命令会覆盖image中的CMD 命令，如果不声明默认使用image的CMD

   version: "3"
   services:
     web:
       image: python
       command: /bin/sh -c "python -m http.server"
       #command: ["python","-m","http.server"]
   

4. ports 指定了端口的映射

   version: "3"
   services:
     web:
       image: python
       ports:
         - "500:8000"
       command: /bin/sh -c "python -m http.server"
       #command: ["python","-m","http.server"]
   

5. working_dir

   version: "3"
   services:
     web:
       image: python
       ports:
         - "500:8000"
       # 覆盖image中的WORKDIR
       working_dir: /tmp
       command: /bin/sh -c "python -m http.server"
   

6. build和 image指定容器使用那个镜像或dockerfile

   version: "3"
   services:
     web:
       build: .
       ports: ["500:80"]
       # 覆盖image中的WORKDIR
       working_dir: /root
       # 覆盖镜像中的CMD
       command: /bin/sh -c "python -m http.server 80"  
   

   # Dockerfile
   FROM python
   WORKDIR /bin
   CMD ["python","-m","http.server"]
   

7. expose指定容器对外暴露的端口

   version: "3"
   services:
     web:
       build: .
       expose:
         - "80"
       ports: ["500:80"]
       # 覆盖image中的WORKDIR
       working_dir: /root
       # 覆盖镜像中的CMD
       command: /bin/sh -c "python -m http.server 80"
   

   # Dockerfile
   FROM python
   WORKDIR /bin
   CMD ["python","-m","http.server"]
   

8. volumes

   [INFO]

   docker-compose down --volumes #移除挂载

   version: "3"
   services:
     web:
       build: .
       expose:
         - "8000"
       ports:
         - "500:8000"
       volumes:
         - "/tmp:/tmp"
       working_dir: "/tmp"
       command: /bin/sh -c "python -m http.server"
   

9. network_mode host 、bridge、none、container:containername

   version: "3"
      services:
        web:
          image: python
          expose:
          - "8000"
          ports:
          - "500:8000"
          volumes:
          - "/tmp:/tmp"
          working_dir: "/tmp"
          command: /bin/sh -c "python -m http.server"
          network_mode: host
   

10. resatart

    version: "3"
    services:
      web:
        image: python
        expose:
        - "8000"
        ports:
        - "500:8000"
        volumes:
        - "/tmp:/tmp"
        working_dir: "/tmp"
        command: /bin/sh -c "python -m http.server"
        network_mode: host
        restart: unless-stopped
        #restart: always
    

11. pid 与宿主机的共享ipc名称空间

    version: "3"
    services:
      web:
        image: python
        expose:
        - "8000"
        ports:
        - "500:8000"
        volumes:
        - "/tmp:/tmp"
        working_dir: "/tmp"
        command: /bin/sh -c "python -m http.server"
        network_mode: host
        restart: unless-stopped
        #restart: always
        pid: host
    

12. depends_on

13. links

14. 环境变量

    • 从文件中加载
    • 从系统变量中获取
    • 容器中设定变量
    • 在容器中指定envfile
    • 在使用docker-compose -e

    [INFO]

    1.28版本之前从当前目录中查找.env

    1.28 之后从project 的目录下寻找.env

    可以通过docker-compose --env-file ./config/.env.dev up 指定环境变量的文件

    # 从文件中加载 
    cat .env
    ContainerPort=8000
    port=500
    

      version: "3"
      services:
        web:
          build: python
          expose:
            - "${ContainerPort}"
          ports:
            - "${port}:${ContainerPort}"
          volumes:
            - "/tmp:/tmp"
          working_dir: "/tmp"
          command: /bin/sh -c "python -m http.server"
    

    可以通过 docker-compose config 验证变量的解析情况

      # 从系统变量中获取变量
      ]#  export port=1000
    

      version: "3"
      services:
        web:
          build: python
          expose:
            - "${port}"
          ports:
            - "${port}:8000"
          volumes:
            - "/tmp:/tmp"
          working_dir: "/tmp"
          command: /bin/sh -c "python -m http.server"
    

    可以通过 docker-compose config 验证变量的解析情况

     # 容器中设定变量environment
     version: "3"
      services:
        web:
          build: python
          environment:
          # 可以只用key 没有value
            - ContainerPort
            - port=500
          expose:
            - "${port}"
          ports:
            - "${port}:8000"
          volumes:
            - "/tmp:/tmp"
          working_dir: "/tmp"
          command: /bin/sh -c "python -m http.server"
    

    可以通过 docker-compose config 验证变量的解析情况

    # 在容器中指定envfile
    version: "3"
      services:
        web:
          build: python
          env_file:
          - ./web-variables.env
          expose:
            - "${port}"
          ports:
            - "${port}:8000"
          volumes:
            - "/tmp:/tmp"
          working_dir: "/tmp"
          command: /bin/sh -c "python -m http.server"
    

    可以通过 docker-compose config 验证变量的解析情况

         #在使用docker-compose -e 
         docker-compose run -e DEBUG=1 web python console.py
    

15. profiles

    [INFO]

    当docker-compose up 时不启用带有profiles标签的服务
    docker-compose --profile profile的标签 up 才会启用
    如下例子

    docker-compose up 只会启动backend和db 容器，
    docker-compose --profile frontend --profile debug up 启动所有容器
    COMPOSE_PROFILES=frontend,debug docker-compose up 启动所有容器

      version: "3.9"
      services:
        frontend:
          image: frontend
          profiles: ["frontend"]
    
        phpmyadmin:
          image: phpmyadmin
          depends_on:
            - db
          profiles:
            - debug
    
        backend:
          image: backend
    
        db:
          image: mysql
    

简单的web负载均衡事例

version: '3'
services:
  lb:
    image: nginx
    ports:
      - "500:80"
    volumes:
      - /tml:/html
      - .:/etc/nginx/conf.d/
    links:
      - web
      - web1
      - web2
    command: ["nginx","-g","daemon off;"]
  web:
    image: python
    command: ["python","-m","http.server"]
    expose:
      - "8000"
    working_dir: "/tmp"
  web1:
    image: tomcat
    command: ["bin/catalina.sh","run"]
    expose:
      - "8080"

  web2:
    image: nginx
    command: ["nginx","-g","daemon off;"]
    expose:
      - "80"

docker-compose 命令

docker-compose up
docker-compose up -d
docker-compose run web env
docker-compose up -d --scale web=5
docker-compose ps
docker-compose down
docker-compose stop
docker-compose --env-file ./config/.env.dev up 
docker-compose --profile debug up
docker-compose --profile frontend --profile debug up
docker-compose config -f test.yaml  docker-compose config -f test.yaml 

使用docker-compose config 查看docker-compose.yml 中变量解析后的内容

docker-compose --env-file ./config/.env.dev config