I’m using docker compose and Flask python.
I’m trying to run an old application but I get sqlalchemy.exc.OperationalError: (pymysql.err.OperationalError) (2003, "Can't connect to MySQL server on 'XXX.XXX.XXX.XXX' (timed out)") (Background on this error at: http://sqlalche.me/e/e3q8)

Here is my docker-compose.yaml

version: "3.2"

services:
  nginx:
    build:
      # context: ./nginx
      context: $CONTEXT
      args:
        # DOMAIN: ${DOMAIN}
        # EMAIL: ${EMAIL}
        DOMAIN: mydomain.com
        EMAIL: [email protected]
        FLASK: XXX.XXX.XXX.XXX

        DOMAIN_WP: help.mydomain.com
        EMAIL_WP: [email protected]
        APP_WP: 172.19.0.1
    ports:
      - 80:80
      - 443:443
    volumes:
      - /etc/letsencrypt/live:$SSL_STORAGE
    depends_on:
      - app
# main app
  app:

    build: ./
    container_name: app_app_1

    hostname: localhost
    environment:

      MYSQL_ROOT_PWD: root
      MYSQL_USER: user_repo
      MYSQL_USER_PWD: 123456
      MYSQL_USER_DB: user_repo
      ENVT: test
      
    volumes:
      - ./:/app
      - /var/lib/onlyoffice/documentserver/App_Data/cache/files/forgotten:/app/oo-files
    ports:
      - "127.0.0.1:3302:3306"
      - "8095:8080"

and my python config.py file:

# DATABASE CONFIG
    MYSQL_DATABASE_USER = 'user_repo'
    MYSQL_DATABASE_PASSWORD = '123456'
    MYSQL_DATABASE_DB = 'user_repo'
    MYSQL_DATABASE_HOST = 'localhost'

I have no idea why it is giving an error. I tried to create any necessary MySQL users with no luck.

CREATE USER 'user_repo'@'XXX.XXX.XXX.XXX' IDENTIFIED BY '123456';
GRANT ALL PRIVILEGES ON *.* TO 'user_repo'@'XXX.XXX.XXX.XXX' WITH GRANT OPTION;