在docker容器中时无法连接到MySQL（python MySQL连接器）

我有一个基于Python Flask的应用程序，需要连接到数据库

version: "3.7"

networks:
  localdev:
    driver: bridge

services:
  sysman-db:
    image: mysql:8.0
    container_name: sysman-db
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    ports:
      - "4000:3306"
    environment:
      MYSQL_ROOT_PASSWORD: xxxxx
    volumes:
      - ./database/docker:/etc/mysql/conf.d
      - ./database/schema.sql:/docker-entrypoint-initdb.d/dump0.sql
    networks:
      - localdev

  sysman:
    build:
      context: .
      dockerfile: Dockerfile.sysman
    container_name: sysman
    depends_on:
      - sysman-db
    ports:
      - "3030:3030"
    networks:
      - localdev
    links:
      - lsm-db

Flask应用程序连接到MySql，它有一个重试方法，因为Docker在数据库初始化完成之前启动了sysman

即使数据库已启动，我仍能得到：

sysman    | 2020-02-11 13:55:08 [ERROR] Unable to connect to db, reason: 2003: Can't connect to MySQL server on 'sysman-db:4000' (111 Connection refused)
sysman    | 2020-02-11 13:55:18 [ERROR] Unable to connect to db, reason: 2003: Can't connect to MySQL server on 'sysman-db:4000' (111 Connection refused)
sysman    | 2020-02-11 13:55:28 [ERROR] Unable to connect to db, reason: 2003: Can't connect to MySQL server on 'sysman-db:4000' (111 Connection refused)
sysman    | 2020-02-11 13:55:38 [ERROR] Unable to connect to db, reason: 2003: Can't connect to MySQL server on 'sysman-db:4000' (111 Connection refused)

数据库连接是：

dbConfig = { 'host' : '127.0.0.1', 'port' : 4000, 'user' : user, 
             'password' : password, 'database' : database }
connPool = mysql.connector.pooling.MySQLConnectionPool(pool_name='myPool',
                                                       pool_size=3,
                                                       pool_reset_session=True,
                                                       **dbConfig)

---

如果我自己打开MySql容器，那么可以使用MySql-u root-p-p4000进行连接。

您的sysman容器应该使用sysman db:3306（而不是4000）连接到数据库容器。请记住，这是两个服务之间的通信，因此发布的端口不算在内。

您正在尝试连接未运行mysqld的flask容器的本地主机。已发布端口的4000个端口计数。2个集装箱应通过3306端口通话

试试这个：

dbConfig = { 'host' : 'sysman-db', 'port' : 3306, 'user' : user, 
             'password' : password, 'database' : database }

---

谢谢你，我一直在用我的头撞着这堵众所周知的砖墙：（@Lucythonas很高兴我能帮上忙；）希望解释也足够清楚。是的，我犯了致命的错误，假设它是如何工作的：P