customizing mariadb role

Hi there,

I would like to customize some values that are stored in
roles/mariadb/templates/50-server.cnf.j2

From what I can see, some values can be but not all of them like max_allowed_packet.
There are several ways to do it but I am wondering what would be the best way in order to keep trellis logic.

I also would like to add some values related to mysql replication.

Regards