Re: sdnotify-wrapper but the other way around

Jan Braun <[email protected]> Sun, 2 Mar 2025 12:10:09 +0100

Newsgroups	gmane.comp.sysutils.supervision.general
Message-ID	<Z8Q8kWqePuGArJiL@abakus>

Hey,
[email protected] schrob:
> Here's sdnotify-wrapper[1] but inverted: it pretends to be systemd's
> side of the sd-notify protocol, listens for an sd-style "READY=1", and
> then notifies s6 on behalf of the ready service.

The cleverness of s6's readiness protocol is that it will recognize
systemd's "READY=1\n" output as an instance of its own "arbitrary bytes,
then a newline" readiness notification. So your wrapper should usually
not be necessary.
There could be programs using sd_notify to signal other things besides
readiness (notifying a "WATCHDOG=1" seems to exist), in which case such
a wrapper may indeed be needed for correct operation.
But grepping tailsacale's source indicates that they only sdnotify
readiness, thus you should get working and correct readiness status by
just setting up the notification-fd.

> I've attached a rough implementation of this idea, [...]

No attachment arrived here.

Cheers,
    Jan

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