我搞不懂这个。下面是我的docker文件。这是一个docker swarm，但都在一台主机上（只是测试设置）。我正在尝试向mysql添加一个应用程序用户，以便web容器可以访问db容器的mysql服务器。我不想使用通用主机通配符，因为db容器的mysql端口将向世界开放。有没有办法自动完成？我已尝试对主机使用“web”，但总是因为“10.0.0.x”错误而拒绝访问。
谢谢！
更新sql:

UPDATE mysql.user SET host = 'web' where user = 'app';
FLUSH PRIVILEGES;

连接错误：

Access denied for user 'app'@'10.0.1.4' (using password: YES)

docker撰写：

version: "3.4"
services: 
    web:
        image: app:latest
        ports: 
            - 4000:80
        # networks: 
            # - appnet
        volumes:
            - uploads:/app/uploads
        secrets:
            - dbapp
            - mailkey
            - sessionsecret
        deploy:
            replicas: 1
            restart_policy:
                condition: on-failure
                delay: 1s
                max_attempts: 10
    redis:
        image: redis:alpine
        # networks:
            # - appnet
    db:
        image: mysql:5.7
        # networks:
            # - appnet
        secrets:
            - dbroot
            - dbapp
        environment:
            MYSQL_DATABASE: "app"
            MYSQL_USER: "app"
            MYSQL_ROOT_PASSWORD_FILE: /run/secrets/dbroot
            MYSQL_PASSWORD_FILE: /run/secrets/dbapp
        volumes:
            - db:/var/lib/mysql
            - ./scripts:/docker-entrypoint-initdb.d
secrets:
    dbroot:
        external: true
    dbapp:
        external: true
    sessionsecret:
        external: true
    mailkey:
        external: true
volumes:
    uploads:
    db:

# networks:

    # - appnet