Running under systemd

contrib/torrnado.service runs the daemon as a system service under its own unprivileged user, with StateDirectory=torrnado for the session file and socket. Its header carries the install steps; make systemd-test runs them and the unit against a real systemd in a container (Dockerfile.systemd), including systemctl restart keeping the torrent list, systemctl reload reopening the log, and a SIGKILLed daemon being brought back.

Worth knowing on a systemd box: every client starts a daemon itself when nothing answers the socket. Run torrnado list while the service is stopped, or during the seconds it takes to restart, and you get a second daemon that systemd does not manage -- holding the lock the service is about to want, which makes the service fail to start with another daemon already holds .../daemon.sock.lock in the journal. Kill that one (pkill -u torrnado torrnado) and start the service again.