Important Update 2020.05.24 After upgrading to 20.03 version of NixOS, the docker container starts to use the container’s actual name instead of its systemd service’s name to address the container. This means that to specify the database container from the filerun web server’s container, you need to change the value of FR_DB_HOST from docker-filerun-mariadb.service to filerun-mariadb.
The Problem One of the biggest convenience you have in NixOS is that many of the services you want to run are already coded as a “service”.