On Wednesday 02 March 2005 05:16 pm, Scott Gifford wrote:
> Patrick Campbell <PCampbell@xxxxxxxxxxxxxxxxxxxx> writes:
>
> [...]
>
> > I'm wondering if I should reconsider using supervise.
> >
> > I tend to feel like it "over complicates" things and also feel like if a
> > program is going to "crash" or whatever qmail might do, sometimes its
> > just best to let it.
>
> One nice thing about it is it gives you a consistent interface to
> everything that runs under it; you don't have to remember to use
> apachectl for Apache, kill qmail-send manually for qmail, send a HUP
> signal to inetd.
this, in my opinion, is the most important advantage to using supervise and
daemontools. Portable, easy to use startup scripts. And a very simple
interface to help write portable utilities for starting/stopping/managing
these services (Dave Sill's 'qmailctl' script is an excellent example of
utilizing these features)
> Starting things back up automatically is generally nice; supervise
> limits how often it will restart things, so it doesn't tend to take
> down machines frantically restarting services.
.... by waiting one second before trying again, which is plenty enough,
generally.
> And especially on
> Linux with its out-of-memory killer, sometimes a process can die for
> no good reason and needs to be restarted.
yes, but the oom-killer is very buggy and I don't believe it is recommended
that anyone use it yet.
> On the other hand, I think there are some general security
> disadvantages to automatically restarting services, especially in the
> face of buffer overflow attacks that require the attacker to guess
> memory locations and such.
using svc -o instead of svc -u can take care of this. You can have a startup
script that does svc -o on your services, this should make them stay down the
next time they go down.
-Jeremy
--
Jeremy Kitchen ++ Systems Administrator ++ Inter7 Internet Technologies, Inc.
jeremy@xxxxxxxxxx ++ www.inter7.com ++ 866.528.3530 ++ 815.776.9465 int'l
kitchen @ #qmail #gentoo on EFnet IRC ++ scriptkitchen.com/qmail
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