supervision - discussion about system services, daemon supervision, init, runlevel management, and tools such as s6 and runit
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* s6-svscan shutdown notification
@ 2022-02-24  1:27 Jan-willem De Bleser
  2022-02-24  5:04 ` Laurent Bercot
  0 siblings, 1 reply; 5+ messages in thread
From: Jan-willem De Bleser @ 2022-02-24  1:27 UTC (permalink / raw)
  To: supervision

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Hi,

What's the cleanest way to wait on s6-svscan to shut down after issuing of
a SIGTERM (say s6 via-svscanctl -t)?

I'm using s6 to manage daemons in FreeBSD jails, and am trying to work out
the cleanest way to shut things down. I want to use the built-in 'jail'
command for this since it takes care of host operations like unmounting the
jail filesystems and recovering/freeing network interfaces, but in and of
itself it just issues a SIGKILL inside the jail. It can optionally run a
shutdown script, say one that calls "s6-svscanctl -t", but I need some way
to delay the ending of that script until the supervision tree has actually
shut down: some of the managed processes will need to flush data to disk.

Looking at the documentation, my only option appears to be to check if the
return code of s6-svscanctl is 100, or maybe to monitor for the existence
of .s6-svscan/control (not sure if it's removed on exit). Are there any
other ways to monitor s6-svscan?

Is the communication protocol between s6-svscanctl and s6-svscan via
.s6-svscan/control documented anywhere? These jails are service jails with
no shells installed, so if I have to check for a return code of exactly 100
then I'll have to write a specific tool for that, at which point it may be
better for me to write a 'scanwait' tool of some sort that just checks for
existence.

Cheers,
Jw

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2022-02-26 16:13 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-24  1:27 s6-svscan shutdown notification Jan-willem De Bleser
2022-02-24  5:04 ` Laurent Bercot
2022-02-24  5:16   ` Jan-willem De Bleser
2022-02-25 16:52     ` Jan Bramkamp
2022-02-26 16:12       ` Jan-willem De Bleser

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