Re: Dependencies in S6

From: Steve Litt <>
Date: Wed, 21 Oct 2020 15:14:45 -0400

On Wed, 21 Oct 2020 13:26:25 +0000
"Laurent Bercot" <> wrote:

> "A is ready" means:
> - if A is a oneshot: when the script has completed
> - if A is a longrun:
> * if there is a notification-fd file in the service definition
> directory: when the daemon has notified readiness
> * if there is no such file: as soon as the run script has started
> (which is not a good readiness indicator; it is akin to starting B
> _right after A_, essentially in parallel, so you may have race
> conditions here - which is why you should always use readiness
> notifications.)

I seem to remember that s6 also has specially named shellscript to
determine dependency readiness. So, for instance, process B requires a
functioning network, the shellscript would contain a ping command or an
ip command. I do this all the time, informally.

Steve Litt
Autumn 2020 featured book: Thriving in Tough Times
Received on Wed Oct 21 2020 - 19:14:45 UTC

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