Re: How to use s6 and s6-rc together

From: Steve Litt <slitt_at_troubleshooters.com>
Date: Thu, 18 May 2017 21:32:11 -0400

On Fri, 19 May 2017 00:02:00 +0200
Luis Ressel <aranea_at_aixah.de> wrote:

> On Thu, 18 May 2017 16:28:17 -0500
> Robert Hill <hilljamesrobert_at_gmail.com> wrote:
>
> > The overview for s6-rc
> > <http://skarnet.org/software/s6-rc/overview.html> mentions that:
> >
> > > the chosen init should make sure that a s6 supervision tree is up
> > > and running. s6-rc will only work if there is an active s6-svscan
> > > process monitoring a scan directory.
> >
> > This is a little confusing to me, and I am sure I am not
> > understanding correctly. If s6-svscan is monitoring a scan
> > directory, won't all the processes in that scan directory already
> > have been started by the s6-supervise instances that get started by
> > s6-svscan? I would like to use s6-rc to start all services and s6
> > to supervise them once started.
>
> Yes, when your init exec's into s6-svscan, it will immediately start
> all services in the scandir (unless the corresponding servicedir
> contains a down file).
>
> However, the scandir will typically be empty at this point (it may
> contain an early getty service). It is only populated with services
> once you call s6-rc-init (to be exact, s6-rc-init creates the
> servicedirs in /run/s6-rc/servicedirs and then symlinks them into the
> scandir). s6-svscan will still not start the services, though, since
> all the servicedirs created by s6-rc-init will contain a down file.
> They will only be started once you call s6-rc -u change ok-all (ok-all
> being the s6-rc bundle containing all your services).

This sounds something like the way I incorporated determinate startup
order to daemontools, runit and s6 using LittKit:

http://troubleshooters.com/projects/littkit/README

http://www.troubleshooters.com/linux/diy/suckless_init_on_plop.htm#littkit_introduction

If you're using down files to determine startup order, do you have a
different filename (LittKit calls it 'reallydown") to take over the
former functionality of the down file (to make the service down for
awhile, through reboots)?

Thanks,

SteveT

Steve Litt
May 2017 featured book: Twenty Eight Tales of Troubleshooting
http://www.troubleshooters.com/28
Received on Fri May 19 2017 - 01:32:11 UTC

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