On 28/07/2015 16:59, Patrick Mahoney wrote:
If I understand correctly, any 'readiness' reporting mechanism must originate
from the run script (to inherit notification-fd).
Yes.
Do you have any suggestions for adding readiness support to a daemon *without
modifying that daemon*?
It's still possible, and exactly as hackish as before. :)
Previously, I had been using s6-log to match a particular line from the
daemon's log output (e.g. "$service is ready"), sending the matched line to
something like 'cd .. s6-notifywhenup echo' (note: a child process of run/log,
not run).
Yes, I remember that case.
To support the same through the notification-fd, I can imagine a rough scheme
such as:
in run:
background { if { s6-ftrig-wait fifodir U } fdmove 1 3 echo }
... run the daemon
in log/run
pipeline -w
{
forstdin -d"\n" i s6-ftrig-noitfy ../fifodir U
}
s6-log
- +"daemon is ready" 1
+ t n20 !"gzip -nq9" logdir
Yes, something like that would work. No need for a fifodir: a simple
named pipe would do, just make sure only your logger writes to it
and only your service reads from it.
My take would be something like:
./run:
fdmove -c 2 1
foreground { mkfifo readiness-fifo }
background -d
{
fdmove 1 3
redirfd -r 0 readiness-fifo
head -n 1
}
fdclose 3
daemon
./log/run:
redirfd -w 1 ../readiness-fifo
s6-log - +"daemon is ready" 1
rest-of-your-logging-script
--
Laurent
