[systemd-devel] Complex supervision structures/delegating watchdog?

[Holger Freyther]

Hi,

for one application we will spawn one or more pppd daemons. Once
a link is up I would like to monitor them. The closest thing that
I can do right now is "systemctl start mon@$PPP_IFACE" from within
a /etc/ppp/ip-up.d/mon file.

In case I consider the link broken or I want to bring it down, I
don't know how to do it. What options do I have? I can look at 
/run/$PPP_IFACE.pid and then send a SIGHUP to the task (this
requires that the monitor app is allowed to do that).

What would be neat is that if I could spawn a "watchdog" from
with-in /etc/ppp/ip-up.d/mon for the existing service and that
when the application exits (or doesn't respond/send watchdog
messages to systemd) the "parent" will be stopped.

Is something like this already possible or wanted behavior? How
would you handle that?

holger