mysql - 为什么无法访问mysql服务？

Question

在建立连接期间，服务名称未解析为 mysql 的主机。服务名称是 mysqldb 但是当我在连接数据库时将它用作主机时，它会产生错误。

已解决:问题出在容器的启动上。 flask 容器没有等待 mysql 容器就绪。这就是它早早退出的原因。我通过在失败时对 Flask 容器使用重启策略进行了快速修复。

docker-compose.yml 文件:

version: '3.7'
services:
  mysqldb:
    image: mysql:latest
    environment:
        MYSQL_ROOT_PASSWORD: root
        MYSQL_DATABASE: myapp
        MYSQL_PASSWORD: root
    ports:
      - "3333:3306"
    volumes:
      - ./db:/docker-entrypoint-initdb.d/:ro
  flask-app:
    build: .
    ports:
      - "5000:5000"
    depends_on:
      - mysqldb

使用 mysql.connector

mydb = mysql.connector.connect(host="mysqldb", user="root",password="root", database="myapp", port="3306")

这是我遇到的错误

flask-app_1  | Traceback (most recent call last):
flask-app_1  |   File "/usr/local/lib/python3.7/site-packages/mysql/connector/network.py", line 509, in open_connection
flask-app_1  |     self.sock.connect(sockaddr)
flask-app_1  | ConnectionRefusedError: [Errno 111] Connection refused
flask-app_1  | 
flask-app_1  | During handling of the above exception, another exception occurred:
flask-app_1  | 
flask-app_1  | Traceback (most recent call last):
flask-app_1  |   File "app.py", line 10, in <module>
flask-app_1  |     mydb = mysql.connector.connect(host="mysqldb", user="root",password="root", database="myapp", port="3306")
flask-app_1  |   File "/usr/local/lib/python3.7/site-packages/mysql/connector/__init__.py", line 179, in connect
flask-app_1  |     return MySQLConnection(*args, **kwargs)
flask-app_1  |   File "/usr/local/lib/python3.7/site-packages/mysql/connector/connection.py", line 95, in __init__
flask-app_1  |     self.connect(**kwargs)
flask-app_1  |   File "/usr/local/lib/python3.7/site-packages/mysql/connector/abstracts.py", line 716, in connect
flask-app_1  |     self._open_connection()
flask-app_1  |   File "/usr/local/lib/python3.7/site-packages/mysql/connector/connection.py", line 206, in _open_connection
flask-app_1  |     self._socket.open_connection()
flask-app_1  |   File "/usr/local/lib/python3.7/site-packages/mysql/connector/network.py", line 512, in open_connection
flask-app_1  |     errno=2003, values=(self.get_address(), _strioerror(err)))
flask-app_1  | mysql.connector.errors.InterfaceError: 2003: Can't connect to MySQL server on 'mysqldb:3306' (111 Connection refused)
flaskapp_flask-app_1 exited with code 1

这是 docker-compose ps

Name                     Command             State                 Ports              
----------------------------------------------------------------------------------------------
flaskapp_flask-app_1   python3 app.py                Up      0.0.0.0:5000->5000/tcp           
flaskapp_mysqldb_1     docker-entrypoint.sh mysqld   Up      0.0.0.0:3333->3306/tcp, 33060/tcp

docker 网络 ls

NETWORK ID          NAME                DRIVER              SCOPE
509b1e597bc4        bridge              bridge              local
b841295e0dc6        flaskapp_default    bridge              local
2cd96006df91        host                host                local
260025d73006        none                null                local

Answer 1

正如有人在您的评论中所述，您需要配置networks 或links。

这是一个如何使用 docker-compose.yml 示例配置网络的示例:

version: '3.7'
services:
  mysqldb:
    image: mysql:latest
    environment:
        MYSQL_ROOT_PASSWORD: root
        MYSQL_DATABASE: myapp
        MYSQL_PASSWORD: root
    ports:
      - "3333:3306"
    volumes:
      - ./db:/docker-entrypoint-initdb.d/:ro
    networks:
      - mynetwork
  flask-app:
    build: .
    ports:
      - "5000:5000"
    depends_on:
      - mysqldb
    networks:
      - mynetwork
networks: 
  mynetwork:

mysqldb 和flask-app 都将加入mynetwork 网络。

我通常会过度测试，所以我也会 docker-compose exec flask-app bash 并运行 ping mysql 命令(假设安装了 ping)来确保你在您的两个容器之间建立网络连接。

此外，虽然我提到了 links，但您应该避免使用它，因为它是一个已弃用的功能，可能会在未来的 docker-compose 版本中被删除。