docker-compose自定义网络，固定容器ip地址

由于默认的bridge桥接网络，重启容器后会改变ip地址。在一些场景下我们希望固定容器IP地址。
docker-compose是docker的一个编排工具，相对于命令模式创建网络，容器等。使用配置文件相对来说更方便，可追溯问题。

直接粘贴docker-compose.yml文件

version: '2'
services:
   nginx:
      image: nginx:1.13.12
      container_name: nginx
      restart: always
      networks:
         extnetwork:
            ipv4_address: 172.19.0.2
 
networks:
   extnetwork:
      ipam:
         config:
         - subnet: 172.19.0.0/16
           gateway: 172.19.0.1

说明：
gateway是网关地址
subnet是网络号段
extnetwork是自定义的网络名称

上面配置中我们的nginx容器固定ip为172.19.0.2

示例，自定义网络模式：

version: '2'
services:
   nginx:
      image: nginx:1.13.12
      container_name: nginx
      restart: always
      networks:
         extnetwork:
      ports:
         - 80:80
      volumes:
         - '/nginx/conf.d:/etc/nginx/conf.d'
   nginx2:
      image: nginx:1.13.12
      container_name: nginx2
      restart: always
      networks:
         extnetwork:
            ipv4_address: 172.19.0.2
         
   db:
     image: mysql:5.7
     container_name: db
     volumes:
       - /var/lib/mysql:/var/lib/mysql
     restart: always
     networks:
         extnetwork:
     ports:
         - 3306:3306
     environment:
       MYSQL_ROOT_PASSWORD: wordpress
       MYSQL_DATABASE: wordpress
       MYSQL_USER: wordpress
       MYSQL_PASSWORD: wordpress      
   
   wordpress:
      image: wordpress:latest
      container_name: wordpress
      depends_on:
         - db
      ports:
         - "8000:80"
      restart: always
      networks:
         extnetwork:
      environment:
         WORDPRESS_DB_HOST: db:3306
         WORDPRESS_DB_NAME: wordpress
         WORDPRESS_DB_USER: wordpress
         WORDPRESS_DB_PASSWORD: wordpress
networks:
   extnetwork:
      ipam:
         config:
         - subnet: 172.19.0.0/16
           gateway: 172.19.0.1