Environment & Version

• Docker Compose version v2.12.0
• Version: 2024.06

Description

After upgrading to the latest 2024.06 version the admin container is unable to connect to an external MariaDB database due to incompatible collation.

Replication Steps

• Use MariaDB as an external database backend. In my case version 11.5.2.
• Update mailu to the latest version.

Observed behaviour

The admin container failes with

sqlalchemy.exc.DatabaseError: (mysql.connector.errors.DatabaseError) 1273 (HY000): Unknown collation: 'utf8mb4_0900_ai_ci'

Expected behaviour

Admin container should be able to connect to either mysql or mariadb backends.

Cause

MariaDB has no support for utf8mb4_0900_ai_ci which is the new default since MySQL version 8.0. In the current sqlalchemy version shipped with mailu, the mysqlconnector sets utf8mb4_0900_ai_ci as the collation to use when connecting. This causes all MariaDB connections to fail.

Workaround

Overwrite the default collation for mysqlconnector in the connection string in mailu.env:

SQLALCHEMY_DATABASE_URI=mysql+mysqlconnector://<user>:<passwd>@<host>/<database>?collation=utf8mb4_unicode_ci

Possible Solution

Include the "mariadbconnector" module for sqlalchemy and use it in the sqlalchemy connection string. Currently it is not included with the version shipped by mailu.