1 Introduction

Docker Compose is a tool Docker containers choreographed, definitions and applications running multiple containers, you can start a command multiple containers.

Use Compose basically divided into three steps:

Operating environment Dockerfile defined applications
Each service docker-compose.yml up the application of the definition
docker-compose up to start the entire application

Compose and Docker compatibility

compose file format version	docker version
3.4	17.09.0+
3.3	17.06.0+
3.2	17.04.0+
3.1	1.13.1+
3.0	1.13.0+
2.3	17.06.0+
2.2	1.13.0+
2.1	1.12.0+
2.0	1.10.0+
1.0	1.9.1.+

2. Install Compose

Can be downloaded directly from github, the premise must first install Docker, version to 1.9.1 above

Note that Compose 1.8.0 requires Docker Engine 1.10.0 or later for version 2 of the Compose File format, and Docker Engine 1.9.1 or later for version 1.

# curl -L https://github.com/docker/compose/releases/download/1.8.0/docker-compose-`uname -s`-`uname -m` > /usr/local/bin/docker-compose
# chmod +x /usr/local/bin/docker-compose

Scripts can also be used run.sh pip or the official website of the installation

After the installation confirmation

# docker-compose --version

3. Compose

3.1 Creating a Python application, use Flask, the value credited Redis

3.1.1 build an application directory, create a Python file

# mkdir python
# cd python

# vi app.py 
from flask import Flask
from redis import Redis

app = Flask(__name__)
redis = Redis(host='redis', port=6379)

@app.route('/')
def hello():
    redis.incr('hits')
    return 'Hello World! I have been seen %s times.' % redis.get('hits')

if __name__ == "__main__":
    app.run(host="0.0.0.0", debug=True)

# vi requirements.txt 
flask
redis

3.1.2 创建 Dockerfile

在同一目录下，创建Dockerfile

# vi Dockerfile 
FROM python:2.7
ADD . /code
WORKDIR /code
RUN pip install -r requirements.txt
CMD python app.py

对上面的Dockerfile做一下简单说明：

容器使用Python 2.7的镜像
将当前目录下文件拷贝到容器内/code
指定工作目录为/code
安装python需要的库：flask, redis
容器执行命令 python app.py

3.1.3 创建编排脚本

在同一目录下，创建 docker-compose.yml

# cat docker-compose.yml 
version: '2'
services:
  web:
    build: .
    ports:
     - "5000:5000"
    volumes:
     - .:/code
    depends_on:
     - redis
  redis:
    image: redis

对上面的编排脚本做一下简单说明：

这个应用定义了两个服务：web, redis
web容器通过当前路径下的Dockerfile生成
web容器内的5000端口映射到主机的5000端口
将当前目录挂载到web容器内/code
web容器依赖于redis容器
redis容器从Docker Hub获取镜像

3.1.4 启动应用

会执行编排脚本，分别制作和抓取web，redis镜像，启动容器

# docker-compose up

3.1.5 访问应用

http://localhost:5000/

3.2 其他命令

3.2.1 daemon模式启动/停止

# docker-compose up -d

# docker-compose stop

3.2.2 查看信息

# docker-compose ps

3.2.3 对容器执行命令（一次）

#docker-compose run services cmd

例如：查看web容器环境变量

# docker-compose run web env

3.3 创建一个Wordpress应用

3.3.1 建立一个应用的目录

# mkdir wordpress
# cd wordpress

3.3.2 创建 docker-compose.yml

# cat docker-compose.yml 
version: '2'
services:
  db:
    image: mysql:5.7
    volumes:
      - "./.data/db:/var/lib/mysql"
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: wordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress

  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    links:
      - db
    ports:
      - "8000:80"
    restart: always
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_PASSWORD: wordpress

MySQL的数据目录挂载到当前目录下，./.data/db不存在时会自动创建。