Consider using tor-instance-create

Currently when the Tor module is setup, we make changes to /etc/tor/torrc. But since that file is owned by the tor debian package, this can cause issues during upgrade (conffile prompt).

The tor package includes a script called tor-instance-create, which sets up a new user and home directory with its own configuration file. So for example we can have a service named tor@plinth, and keep our configuration in /etc/tor/instances/plinth/torrc.