我试着用Docker compose安装一个DB和一个Web服务器。
我的docker-compose文件是：

version: '3.3'
services:
  db:
    image: pix_db
    container_name: pix_db
    image: mysql:5.7
    volumes:
      - db_data:/var/lib/mysql
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: test
      MYSQL_DATABASE: test
      MYSQL_USER: test
      MYSQL_PASSWORD: test
    networks:
    - backend
  api:
    image: pix_api
    container_name: pix_api
    build:
      context: .
      dockerfile: ./Dockerfiles/api/Dockerfile.cpu
    depends_on:
    - media
    - db
    ports:
    - "8080:8080"
    networks:
    - backend

networks:
  backend:
  hidden:

volumes:
  db_data:

当我到达docker文件中的这一行时：

php bin/console assets:install -e prod

它崩溃了几个错误，如：

[Doctrine\DBAL\Exception\ConnectionException]
  An exception occured in driver: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

当我从前面的行构建容器时：命令php bin/console assets:install -e prod在我第一次调用它时崩溃并出现相同的错误。但第二次它成功了：

Installing assets as hard copies.

--- ----------------------------- ----------------
      Bundle                        Method / Error
--- ----------------------------- ----------------
  ✔   NelmioApiDocBundle            copy
      -> web/bundles/nelmioapidoc
  ✔   AppBundle                     copy
      -> web/bundles/app
--- ----------------------------- ----------------

! [NOTE] Some assets were installed via copy. If you make changes to these assets you have to run this command again.

[OK] All assets were successfully installed.