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Auteur: Hendrik Boom
Date:  
À: dng
Sujet: Re: [DNG] tiny service state api [WAS: Fwd: init system agnosticism]
On Sun, Apr 16, 2017 at 05:04:18PM -0400, Hendrik Boom wrote:
> On Sun, Apr 16, 2017 at 09:59:36PM +0200, Enrico Weigelt, metux IT consult wrote:
> > On 15.04.2017 19:50, Steve Litt wrote:
> >
> > > About my characterizations: "Baroque" is a relative thing. What I wrote
> > > was based on "why would you not simply use a process supervisor like
> > > systemd?" If a person has a reason not to use such a supervisor, and in
> > > fact the whole OpenRC init system seems to be based on such objections
> > > to supervisors, then the six system call solution you outline
> > > transitions from "a whole bunch of needless stuff" to "hey, that's a
> > > pretty darn kool solution." So your solution is baroque only so far as
> > > one enjoys using daemontools or similar.
> >
> > If one doesn't want a supervisor, why not just using something like
> > start-stop-daemon ? IIRC, it should handle that quite well.
> >
> > I wonder why that general task of daemonizing cant just be done in a
> > generic separate program and left out of the individual daemons.
> > So, everybody can decide on this own how to actually start/manage
> > the daemons - some use a supervisor, some just call via a daemonizer
> > program from init scripts, etc, etc.
> >
> > By the way: maybe we should write an RFC draft for the whole issue ...
>
> Looked for a relevant RFC. But found only this:
> https://lists.ubuntu.com/archives/kernel-team/2008-December/003628.html
> [RFC] [PATCH] notify init daemon when children are reparented to it
>
> But this doesn't seem to be quite what we want, and I can't say I have
> enough context to understand it.


That so-calledRFC seems to be very much in the style of
requiring the init process to be intimately involved in process
supervision actions, which is a strong constraint on what init systems
can be chosen. And, I suspect, an init system that is so involved is
a potential tool to gradually take over the entire OS, as systemd has
done.

Of course, even with such an init system, it's possible to use the
other mechanisms we have been discussing here to enable specific
daemons to ignore the init system.

-- hendrik

>
> It seemms to follow the practice of creating two processes for a
> daemon, a parent and a child, and then orphaning the child.
> This is not what we seem to be discusison here, and leads to
> init having nontrivial ongoing work.
>
> And although it says [RFC] in the title, it doesn't seem to be an
> official RFC.
>
> -- hendrik
>
> >
> >
> > --mtx
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