Re: [gentoo-server] initng and runscript

[Eric Brown]

On 12/20/05, Kalin KOZHUHAROV <kalin@××××××××.net> wrote:
> Eric Brown wrote:
> > It's not just init scripts that are designed poorly, it's applications
> > that fail to daemonize and dont' return non-zero.  (like apache-1.3,
> > ntp-date, snort, etc.. most servers).
> Yeah, that is the real problem, but that is not fixable immediately.
>
> > I think the new baselayout has some adjustable sleep/checks on by
> > default, but I haven't tries it yet.  I suppose that would work by
> > having the init script sleep for a short time, then check to see if a
> > certain process is running (a dirty hack that's frowned updon by
> > some)...
> >
> > Anyway, I really think this is something worth looking into, either as
> > a separate package that implements some kind of monitoring functions
> > in init scripts, or as a basic set of monitoring functions that are
> > included in baselayout for developers to optionally use.
>
> > While there are options like daemontools and rmon? I don't think they
> > provide a very robust solution to this problem.
> Can you elaborate on this? What is wrong with daemontools?
>
> http://cr.yp.to/daemontools/faq/create.html#why
>
> > Here's an idea:
> >
> > Have users emerge a program that can do some basic things:
> emerge daemontools
>
>
> > 1) check config scripts of running services for variables like:
> >     CHECK_COMMAND
> svstat /service/daemon
>
> >     SLEEP_TIME
> If I get you right, this is hard coded to 1 second for supervise.
>
> >     INIT_SLEEP
> If I get you right, this is hard coded to 1 second for supervise.
>
> >     IF_DOWN_DO_THIS
> Not sure how important is this, but flexibility can be achieved inside the ./run script of the
> daemon. The normal thing is to start it again.
> svc -u /service/daemon
>
> >    (those variables could optionally be implemented per package, or
> > explicitly disabled, they would have sane defaults in a central .conf
> > file for this enhancement package)
> This can be worked on, the start is sys-process/daemontools-scripts.
>
> > 2) is a cron job/daemon that automatically checks all running apps in
> > the current runlevel,  can report problems (send emails, log stuff,
> > etc), can send heartbeat, etc..
> Can you trust cron, started from a init script?
> Instead a script started under supervise, as simple as this:
> #!/bin/bash
>
> sleep 60;
> `svstat /service/* |grep down >/dev/null` && \
>         echo "Something is wrong" | your_favourite_mailer_here
>
> (The above is not tested, just thought of. Feel free to improve).
> (Like there can be intentionally down-ed services -e /service/daemon/down)
>
> > 3) is well documented in the gentoo handbook since it's probably a
> > vital component
> http://cr.yp.to/daemontools.html is a good start, in can be improved for sure.
>
> > To me this kind of thing is probably simple, unixish, and robust
> > enough for most of our needs...
> >
> > Any thoughs?
> Don't top-post :-)
>
> Kalin.
> /known also as Korokoro or tar/
>
> P.S. Whose MTA changes the subject with [OBORONA-SPAM] ? Please remove that; use a custom header
> instead.
>
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>

What I don't like about daemontools is that I like our current init
system, and daemontools just totally replaces it.  With a little
effort, it might be possible to simply supplement the init script
resources we already have.  I would really miss some of the stuff the
gentoo devs made easy for us: automatic dependency handling, ease of
use w/rc-update, simple configuration symatics for a wide range of
daemons (network stuff and drive mounting stuff)...

Anyway, I'm glad you brought up daemontools, there's a lot to learn
from it.  Maybe approaching this problem from the other direction
would even be a good idea: How can we enhance daemontools to create a
new gentoo init script system that's every bit as friendly as the
current one?

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