Docker服务-Mysql容器失败

Question

我正在使用此docker-compose.yml启动docker服务

version: '3'

services:
  wp:
    image: wordpress:latest # https://hub.docker.com/_/wordpress/
    ports:
     - 80:80 # change ip if required
    volumes:
      - ./config/php.conf.ini:/usr/local/etc/php/conf.d/conf.ini
      - ./wp-app:/var/www/html # Full wordpress project
      #- ./plugin-name/trunk/:/var/www/html/wp-content/plugins/plugin-name # Plugin development
      #- ./theme-name/trunk/:/var/www/html/wp-content/themes/theme-name # Theme development
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_NAME: "${DB_NAME}"
      WORDPRESS_DB_USER: root
      WORDPRESS_DB_PASSWORD: "${DB_ROOT_PASSWORD}"
    depends_on:
      - db
    links:
      - db
  pma:
    image: phpmyadmin/phpmyadmin
    environment:
      PMA_HOST: db
      PMA_PORT: 3306
      MYSQL_ROOT_PASSWORD: "${DB_ROOT_PASSWORD}"
    ports:
      - 8080:80
    links:
      - db:db

  db:
    image: mysql:latest # https://hub.docker.com/_/mysql/ - or mariadb https://hub.docker.com/_/mariadb
    ports:
      - 3306:3306 # change ip if required
    command: [
        '--default_authentication_plugin=mysql_native_password',
        '--character-set-server=utf8mb4',
        '--collation-server=utf8mb4_unicode_ci'
    ]
    volumes:
      - db_data:/var/lib/mysql
    environment:
      MYSQL_DATABASE: "${DB_NAME}"
      MYSQL_ROOT_PASSWORD: "${DB_ROOT_PASSWORD}"

volumes:
  db_data:

但是db（mysql）容器由于此错误而失败

time="2019-09-26T12:06:30Z" level=info msg="shim docker-containerd-shim started" address="/containerd-shim/moby/4f6b0c7286856ee9fd726cf1ce957103f62b7f39ee9f321584da250ea3a91acd/shim.sock" debug=false pid=13893
time="2019-09-26T12:06:31Z" level=info msg="shim reaped" id=4f6b0c7286856ee9fd726cf1ce957103f62b7f39ee9f321584da250ea3a91acd
time="2019-09-26T12:06:31.298552013Z" level=info msg="ignoring event" module=libcontainerd namespace=moby topic=/tasks/delete type="*events.TaskDelete"
time="2019-09-26T12:06:31.526719243Z" level=error msg="fatal task error" error="task: non-zero exit (1)" module=node/agent/taskmanager node.id=o5eezulizx214m5effwasb1nc service.id=x1i0e0sea1qi4g8jj2hu3vgvl task.id=zo8oi32rt2w12daqu9x1v7c1l

如果我执行docker-compose up，则一切正常。我正在使用Aws EC2机器（t2.medium）。还有一个.env文件，我在其中设置了DB_NAME和DB_PASSWORD。

谢谢！