Re: Some suggestions about s6 and s6-rc

From: Colin Booth <>
Date: Mon, 21 Sep 2015 07:11:37 -0700

On Sun, Sep 20, 2015 at 9:29 AM, Laurent Bercot
<> wrote:
> On 20/09/2015 18:03, Steve Litt wrote:
>> That's my point exactly. Unfamiliar with the tool, you read the docs,
>> keep reading about "down" in two different contexts, get confused, and
>> say "later days."
> You will not read about "down" in two different contexts in the docs.
> If you had read the docs, you would know that. :-Þ
The concept of a file named "down" is used in both contexts, but the
terminology is consistent , with "down file" being used for longruns
only, and "down script" used for the oneshot stop script. s6-rc talks
about down scripts for oneshots, and the the help pages for s6-rc and
s6-rc-init talk about down files in the classic sense. s6-rc-compile
talks about both but is also consistent, and only mentions down files
to indicate that it ignores them.

>From a "how does it work" perspective, the two uses of down to
indicate an on-disk item are well contained to their respective
sections and it's pretty hard to confuse the two. The down scripts for
oneshots only appear on disk in the pre-compiled source directories.
Once you run s6-rc-compile those files are embedded into the service
database so if you are looking at a scan directory (/run/service for
example) and see files named down, you can be guaranteed that you're
looking at s6-rc state tracking ./down files and not oneshot shutdown
>> Earlier in this thread, you yourself said:
>>> I agree that the name collision is confusing, and it is an annoyance.
> I did say that. The name collision is confusing in this mailing-list at
> this time, because we're talking about s6-rc in a place where people do
> not know about it yet, but do know about supervisors, where "down" has a
> different meaning. When s6-rc is out and it's clear what kind of "down"
> we are talking about, it will not matter anymore.
Agreed, the name collision is only confusing in the "under experienced
humans talking about a thing" context.
>> Or how bout the poor daemontools familiar admin who's heard that s6-rc
>> + s6 is the best and it's daemontools-inspired, so he goes in with a
>> long-established understanding of "down" files and encounters this?
> You don't give Unix admins much credit, do you?
I'm a unix admin and I don't give them much credit ;)
>> OK, then I'm not correctly envisioning what s6-rc really is.
> There. Come back when s6-rc is out and you have read the doc, and
> you will see there's really no reason to panic. It will be okay.
> You'll certainly have some criticism towards s6-rc, and I'll be
> very interested in hearing it, but the use of "down" won't be a
> problem.
So, I think I'm possibly the only non-Laurent person on the mailing
list who uses s6-rc seriously. May I suggest that everyone who wants
to talk about the design of s6-rc but feels like they might be
confused about some parts go and try it out? You don't need to
completely convert your system to do so, a little 4-6 do-nothing
service set with its own s6-svscan and catch-all logger is fine to get
a feel for how the system works (my test rig mostly runs dstat and top
for the longruns, and the oneshots sleep a lot). s6-rc does need s6
and skalib builds that are newer than the current release tarballs but
there are a lot of ways of keeping that separate from your "real"
install if you don't want to rely on the git head.


"If the doors of perception were cleansed every thing would appear to
man as it is, infinite. For man has closed himself up, till he sees
all things thru' narrow chinks of his cavern."
  --  William Blake
Received on Mon Sep 21 2015 - 14:11:37 UTC

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