You can think further, you can build a no-server server; Example let Nginx be running, then forward requests to the database, running the code, query data and responding then shutting down again. Need the service to do something regularly, just trigger that part of the database through crontab.

And yes you can let authorized users add custom code, make it run in the database like a micro-micro-vm and do stuff on triggers etc in the database as well.

This makes it even more powerful, because users can switch code during runtime and you can have multiple users "programming" against the same database at the same time working against the same data.