Configure SQLAlchemy to use the MariaDB/Mysql backend

I discourage you to use an ORM to manage the interactions with the database. Check the alternative solutions.

To use Mysql you'll need to first install (or add to your requirements) pymysql:

pip install pymysql

The url to connect to the database will be: 

'mysql+pymysql://{}:{}@{}:{}/{}'.format(
    DB_USER,
    DB_PASS,
    DB_HOST,
    DB_PORT,
    DATABASE
)

It's probable that you'll need to use UTF8 with multi byte, otherwise the addition of some strings into the database will fail. I've tried adding it to the database url without success. So I've modified the MariaDB Docker-compose section to use that character and collation set:

services:
  db:
    image: mariadb:latest
    restart: always
    environment:
      - MYSQL_USER=xxxx
      - MYSQL_PASSWORD=xxxx
      - MYSQL_DATABASE=xxxx
      - MYSQL_ALLOW_EMPTY_PASSWORD=yes
    ports:
      - 3306:3306
    command:
      - '--character-set-server=utf8mb4'
      - '--collation-server=utf8mb4_unicode_ci'