应用容器无法连接到同一网络中的mysql容器

Question

I have a problem with the docker and containerized apps not connecting to mysql database that is running in a container within the same docker network. My docker-compose.yml looks like this:

version: '3.8'

services:

  mysqlserver:
    image: mysql:5.7.24
    container_name: mysql_app
    networks:
      - somenetwork
    ports:
      - "5647:3306"
    environment:
      MYSQL_DATABASE: database
      MYSQL_USER: USER
      MYSQL_PASSWORD: PASS
      MYSQL_ROOT_PASSWORD: PASS
    command:
      - --max_connections=1000
    restart: always
    volumes:
     - persistent:/var/lib/mysql

  app:
    image: app/appserver:latest
    container_name: app_server
    networks:
      - somenetwork
    ports:
      - "8080:8080"
    depends_on:
      - mysqlserver
    environment:
      SPRING_DATASOURCE_URL: jdbc:mysql://mysqlserver:5647/database?verifyServerCertificate=false&useSSL=false&requireSSL=false&autoReconnect=true

networks:
  somenetwork:
    name:
      somenetwork_share_net

volumes:
  persistent:

And looking at the logs from the app container, I found errors like this:

Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

and

Caused by: java.net.ConnectException: Connection refused (Connection refused) at java.base/java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:na]

Is there something wrong with my docker-compose.yml ? Why the app container cannot connect

Answer 1

You have to use the exposed port on container side 3303 and not the public one 5647 .

Just try

SPRING_DATASOURCE_URL: jdbc:mysql://mysqlserver:3306/database?verifyServerCertificate=false&useSSL=false&requireSSL=false&autoReconnect=true

The port in local network stays the original exposed port. In port section you just define the public ports on the host machine.