Why can't Yii2 connect to the database on other ports than 3306?

Question

MySQL

There is some docker-compose. After building the project, the Yii2 site cannot connect to the database if the port is not specified exactly 3306 (external 3306 is also specified in docker-compose), which causes the error SQLSTATE[HY000] [2002] Connection refused

version: "3.9"

services:
  nginx:
    networks:
      - demo_site
    build:
      context: ./docker/nginx
    ports:
      - "27015:80"
    volumes:
      - ./:/var/www/demo_site.store:ro
      - ./docker/nginx/config:/etc/nginx/conf.d

  php-fpm:
    networks:
      - demo_site
    working_dir: "/var/www/demo_site.store"
    build:
      context: ./docker/php-fpm
    volumes:
      - ./:/var/www/demo_site.store
  mariadb:
    networks:
      - demo_site
    image: library/mysql:5.7
    restart: "always"
    volumes:
      - ./docker/db/sql.sql:/docker-entrypoint-initdb.d/sql.sql
    environment:
      MYSQL_ROOT_PASSWORD: root
    ports:
    - "3361:3306"

networks:
  demo_site:
    driver: bridge

db.php

<?php
return [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=mariadb;port=3361;dbname=demo_site;',
    'username' => 'demo_site',
    'password' => '',
    'charset' => 'utf8',

    // Schema cache options (for production environment)
    'enableSchemaCache' => true,
    'schemaCacheDuration' => 3600 * 24 * 7,
    'schemaCache' => 'cache',
];

What could be the problem? Moreover, you can simply connect to the container with some kind of HeidiSql. But the site does not accept other ports

Answer 1

you connect FROM the container, external:internal port - 3361:3306. and you most likely need the image https://hub.docker.com/_/mysql see description

Answer 2

3361 is a port forwarded to the host system so that you can connect to MySQL without entering the container, but inside the container MySQL listens on port 3306.
If you want to connect to a different port from the container with PHP (why?), change the port in the MySQL config .

'dsn' => 'mysql:host=mariadb;port=3361;dbname=demo_site;',

This will not work, because this port is not available from the container, due to the fact that it is located in the host system, that is, outside the container and the virtual network that unites the containers.