Re: s6 ordering and run-once?

From: Laurent Bercot <ska-supervision_at_skarnet.org>
Date: Wed, 17 Jun 2015 01:07:01 +0200

On 16/06/2015 23:33, Steve Litt wrote:
> Hi all,
>
> I'm studying the s6 website. The only reference I found to controlling
> startup order was a sentence about creating symlinks one by one. I
> found a sentence about run-once types of things (I think the example
> was bringing up the network), but then it didn't tell me *how* to run a
> run-once.
>
> Does anyone know if there are ways to order beyond one symlink at a
> time or s6-svwait?

  Nope, not yet. For now, you'd do just as you do with daemontools or
runit: just start everything, and they'll eventually get there. :)
It is possible to start services one by one, but by hand in a script,
and I haven't met anyone who bothers to do that. I certainly don't.
But there are tools for dependency management, see below.


> Does anyone know how to do a run-once service without putting an
> infinite sleep loop at the end?

  Oneshots are not meant to be supervised. Don't create a service
directory for a oneshot. You'd run your oneshots exactly as you'd do
with runit or daemontools: in a separate script.
  Intermixing oneshots and longruns is complex, it requires real
dependency management, which is more than a process supervision suite
does - supervision only handles longruns.

  There is a dependency manager for s6: http://jjacky.com/anopa/
I also have a dependency manager slowly brewing. Those things are
another world, doing them right is extremely tricky.


> Also, are there any flag files, other than "down", of which I should be
> aware?

  The complete list is at http://skarnet.org/software/s6/servicedir.html

  Good luck!

-- 
  Laurent
Received on Tue Jun 16 2015 - 23:07:01 UTC

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