Docker Compose

WHAT

Docker Compose是用Python编写的工具，并不包含在Docker Engine安装包中。Docker Compose用于解析YML文件并运行YML中定义的容器服务。Docker Compose命令通过调用Docker API完成多容器的创建启动，使用Docker Compose需要自行安装

Docker Compose VS Docker Stack

• docker stack 包含在 swarm mode中，swarm mode 已经被集成到Docker Engine中，由GO语言编写。docker compose 需要自行安装，由Python编写
• docker stack 只支持 version >= 3 的YML定义且部分命令无法生效如 build。docker compose 对YML的不同version处理都没有问题
• docker stack 可以将服务分发到不同的主机上，docker compose 只能将服务分发到同一台主机上

WHY

为什么要使用Docker Compose ?

服务发布

以下是需要容器化的服务

• product-service 商品服务
• shopping-service 商店服务，两套界面
• redis-service 数据缓存
• front-balance 商店服务负载

BEFORE COMPOSE :

docker run -itd --name redis-service --network=backend -p 16379:6379 redis
docker run -itd --name product-service --network=backend -p 15000:5000 8lovelife/product:latest
docker network connect frontend product-service
docker run -itd --name shopping-service-blue --network=frontend -p 28080:80 8lovelife/shopping:blue
docker run -itd --name shopping-service-red --network=frontend -p 18080:80 8lovelife/shopping:red
docker run -itd --name front-balance --network=frontend -p 80:80 8lovelife/frontbalance:latest

AFTER COMPOSE :

docker-compose -f docker-compose-product.yml up -d

HOW

如何使用Docker Compose ?

服务拆分

SHOPPING Dockerfile:

FROM node:11.1.0-alpine as build
WORKDIR /app
COPY package*.json /app/
RUN npm install
COPY ./ /app/
RUN npm run build

FROM nginx:1.17.3-alpine
COPY --from=build /app/build /usr/share/nginx/html
COPY --from=build /app/nginx.conf /etc/nginx/nginx.conf
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]


PRODUCT Dockerfile:

FROM maven:3-jdk-8 as build
RUN mkdir -p /build
WORKDIR /build
COPY pom.xml /build
RUN mvn -B dependency:resolve dependency:resolve-plugins
COPY src /build/src
RUN mvn package -Dmaven.test.skip=true

FROM openjdk:8-jdk-alpine as runtime
EXPOSE 5000
ENV APP_HOME /app
RUN mkdir $APP_HOME
WORKDIR $APP_HOME
COPY --from=build /build/target/*.jar app.jar
ENTRYPOINT [ "sh", "-c", "java $JAVA_OPTS -Djava.security.egd=file:/dev/./urandom -jar app.jar" ]

。。。

YML定义

本文事例使用的docker-compose-product.yml文件内容如下

version: "3"

services: 

  product-service:
    image: "8lovelife/product:latest"
    ports: 
      - "15000:5000"
    networks: 
      - frontend
      - backend
    environment: 
      - REDIS_HOST=redis-service
      - REDIS_PORT=6379
  
  shopping-service-red:
    image: "8lovelife/shopping:red"
    ports: 
      - "18080:80"
    networks: 
      - frontend

  shopping-service-blue:
    image: "8lovelife/shopping:blue"
    ports: 
      - "28080:80"
    networks: 
      - frontend

  redis-service:
    image: "8lovelife/redis:products"
    ports: 
      - "16379:6379"
    volumes: 
      - redis_data:/data
    networks: 
      - "backend"
  
  front-balance:
    image: "8lovelife/frontbalance:latest"
    ports: 
      - "80:80"
    networks: 
      - "frontend"

networks:
  frontend: {}
  backend: {}

volumes: 
  redis_data: {}

构建或拉取镜像

# 绝对路径
build: .

# 相对路径
build: ../path/to/app/

# Git仓库
build: https://url.git

# 指定分支的Git仓库 
build: https://url.git#develop

# 含access_token的Git仓库链接
build: https://<ACCESS_TOKEN>:@github.com/demo.git

配置环境变量

product-service:
  image: "8lovelife/product:latest"
  environment: 
    - REDIS_HOST=redis-service
    - REDIS_PORT=6379

配置网络

product-service:
  image: "8lovelife/product:latest"
  ports: 
    - "15000:5000"
  networks: 
    - frontend
    - backend
    
networks:
  frontend: {}
  backend: {}

配置数据卷

redis-service:
  image: "redis:latest"
  ports: 
    - "16379:6379"
  volumes: 
    - redis_data:/data
  networks: 
    - "backend"
    
volumes: 
  redis_data: {}

构建运行

docker-compose -f docker-compose-product.yml up -d

docker-compose --help compose命令帮助

If you can’t fix it, you gotta stand it. - Jack

Inception