Configure MariaDB server to log slow queries.
Increase the maximum permitted number of simultaneous connections to the MariaDB server.
Load time zone tables into MariaDB server.
Use OpenResty to perform health checks in your cloud environment as it incorporates Nginx, Lua and comes with batteries included.
MariaDB unixODBC driver is not available in the Debian package repository at this moment, but you can build and configure it on your own. It requires some additional work, but in the end it is really worth the time.