Docker compose custom network to achieve fixed container IP address

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

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