Compose: links not working in v2 Compose File

[Evild67]

I tried to upgrade my docker-compose file to V2 but links are not working.

version: '2'
services:
 [...]
  wordpress:
    image: wordpress:4.4.2-fpm
    restart: always
    depends_on:
      - db
    links:
      - db:mysql
    volumes:
      - ./wp:/var/www/html
    environment:
      - WORDPRESS_DB_NAME=....
      - WORDPRESS_TABLE_PREFIX=...

  db:
    image: mariadb:latest
    restart: always
    volumes:
      - ./var/mysql:/var/lib/mysql
    environment:
      - MYSQL_ROOT_PASSWORD=....

Logs :

wordpress_1 | error: missing WORDPRESS_DB_HOST and MYSQL_PORT_3306_TCP environment variables
wordpress_1 |   Did you forget to --link some_mysql_container:mysql or set an external db
wordpress_1 |   with -e WORDPRESS_DB_HOST=hostname:port?

[dnephin]

Those variables have been deprecated for many releases now, and were removed in Docker 1.10: https://docs.docker.com/compose/link-env-deprecated/

You should use the hostname provided by dns: db
The port is already hardcoded (it was in the variable name), so you can just use the port number directly.

[willseward]

My apologies for bumping this, but how do you suggest we provide dependent containers auth creds for a linked container? Are you suggesting we put an entry in each container's environment?