Question 80335 in Docker Question posted in
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Docker compose: mysql port 3306 is already used, container port uses host port?

I already have a Mysql running on host at port 3306.

version: "3"
services:
  db:
    container_name: db_mysql
    image: mysql
    ports:
      - "3309:3306"
    environment:
      - MYSQL_ROOT_PASSWORD=123456

The container msyql port 3306 is mapped to host port 3309. But error:

docker ps -a

CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

docker-compose up

Can't start server: Bind on TCP/IP port: Address already in use
[ERROR] Do you already have another mysqld server running on port: 3306 ?

Is container mysql port 3306 still using the host port 3306?

docker ps -a

CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS                     PORTS     NAMES
103f1e16c782   mysql     "docker-entrypoint.s…"   3 minutes ago   Exited (1) 3 minutes ago             db_mysql

If the ports are commented out, same error.

version: "3"
services:
  db:
    container_name: db_mysql
    image: mysql
    #ports:
      #- "3309:3306"
    environment:
      - MYSQL_ROOT_PASSWORD=123456

UPDATE

After stopping the Mysql on host, it worked. This means that the Docker container (mysql) uses the host port 3306?

Tags:

2

Answers


  1. 0

    I’m going to guess that the default bridge network is mapping directly to the same network that the local mysql server is using. Thus you have a port conflict when starting the container. Add a docker network and use that.

    You can get a list of the networks using docker network ls

    You can then explore the settings of each docker network using docker network inspect <name> where name is one of the network names you get from the ls command. There are a number of built-in networks like bridge. When you don’t specify a network, bridge is what will be used (assuming there is no other local configuration made to have changed this).

    Specify a network for use in your docker-compose orchestration explicitly, which will create a network for use. Frequently you will want more than one network for orchestration of multiple containers, as in the scenario where you have some application servers, a reverse proxy and a backend database like mysql.

    version: "3"
networks: 
  dbnet:
    external: false
services:
  db:
    container_name: db_mysql
    image: mysql
    networks:
      - dbnet
    ports:
      - 3309:3306
    environment:
      - MYSQL_ROOT_PASSWORD=123456
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  2. 0

    Docker compose run command does not create any of the ports specified in the service configuration. This prevents port collisions with already-open ports. If you do want the service’s ports to be created and mapped to the host, specify the –service-ports

    $docker compose run --service-ports SERVICE [COMMAND] [ARGS...]

    https://docs.docker.com/engine/reference/commandline/compose_run/

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