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Accepted
Ben Edwards
Asked: 2020-05-25 15:16:55 +0800 CST

Changing port of mariadb in docker-compose

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I run a number of WordPress sites using docker-compose (and nginx-proxy). So I can use the same docker-compose file for each site I use .env. I want each of the MariaDB containers to use different ports (as they are sharing the same external docker network).

What I have is the below compose file but when I bring it up I get.

MySQL Connection Error: (2002) Connection refused

Previously I was using the same compose file without the ports: section and with the port hardcoded in the WordPress section and it worked.

Where did I go wrong?

docker-compose.yml

version: '3'

services:
  db:
    image: mariadb
    container_name: ${DB_CONTAINER}
    hostname: ${DB_CONTAINER}
    ports:
      - ${DB_PORT}:3306
    volumes:
      - ./db:/var/lib/mysql
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: ${DB_ROOT_PASSWORD}
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: ${DB_WP_PASSWORD}

  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    restart: always
    container_name: ${WP_CONTAINER}
    hostname: ${WP_CONTAINER}
    volumes:
      - ./html:/var/www/html
    expose:
      - 80
    restart: always
    environment:
      VIRTUAL_HOST: ${DOMAINS}
      LETSENCRYPT_HOST: ${DOMAINS}
      LETSENCRYPT_EMAIL: ${EMAIL}
      WORDPRESS_DB_HOST: db:${DB_PORT}
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: ${DB_WP_PASSWORD}

networks:
  default:
    external:
            name: nginx-proxy

.env

DB_CONTAINER=test_click_db
WP_CONTAINER=test_click_wp
DB_PORT=13306
[email protected]
DOMAINS=test.click.tvpp.tv
DB_ROOT_PASSWORD=aabbcc
DB_WP_PASSWORD=xxyyzz
wordpress docker-compose mariadb

2 Answers

  1. Best Answer

    Actually I worked it out the db service needed the following added to environment:

    MYSQL_TCP_PORT: ${DB_PORT}
MYSQL_UNIX_PORT: ${DB_PORT}
    • 2

  2. This line

    WORDPRESS_DB_HOST: db:${DB_PORT}

    should be changed to

    WORDPRESS_DB_HOST: db:3306

    (I guess this actually is what you did previously) The wordpress container will then connect directly to the mariadb container at port 3306 of the container. The db part is resolved by docker network's internal DNS server to the IP address of your mariadb container.

    You don't need this part

    ports:
  - ${DB_PORT}:3306

    It means that docker will map the ${DB_PORT} on your host machine to port 3306 in the service (container), thus you can also reach the DB by connecting to the host machine at port ${DB_PORT}. It's generally only for when you intend to connect to the container from outside the host machine.

    • 1