There were following problems:
- configure.ac wrongly checked for defined HAVE_SYSTEMD; this
wasn't working, so the watchdog code was not compiled in.
Replace library search with explicit version check
- sd_notify() watchdog call was unsetting NOTIFY_SOCKET from env;
this means only first "watchdog ping" was delivered, each
subsequent one did not have socket to be sent to and systemd
was killing service
- after those fixes, enable Watchdog in systemd unit with one
minute intervals
If running under systemd, notify the supervisor about current PID
of Tor daemon. This makes systemd unit simpler and more robust:
it will do the right thing regardless of RunAsDaemon settings.
The rest of the filesystem is accessible for reading only. Still, quoting
systemd.exec(5):
Note that restricting access with these options does not extend to submounts
of a directory that are created later on.
Our current systemd unit uses "Type = simple", so systemd does not expect tor to
fork. If the user has "RunAsDaemon 1" in their torrc, then things won't work as
expected. This is e.g. the case on Debian (and derivatives), since there we pass
"--defaults-torrc /usr/share/tor/tor-service-defaults-torrc" (that contains
"RunAsDaemon 1") by default.
The only solution I could find is to explicitly pass "--RunAsDaemon 0" when
starting tor from the systemd unit file, which this commit does.
