Bug#399930: logrotation race condition with exim writing to logs

[CaT]

On Fri, Nov 24, 2006 at 01:15:01PM +0100, Marc Haber wrote:
> On Fri, Nov 24, 2006 at 10:58:28PM +1100, CaT wrote:
> > On Fri, Nov 24, 2006 at 10:23:38AM +0100, Marc Haber wrote:
> > > On Fri, Nov 24, 2006 at 05:11:25PM +1100, CaT wrote:
> > > > So there is absolutely no need for the create option in logrotate
> > > 
> > > Not having the logs created might break monitoring mechanisms.
> > 
> > Well it is kind of a choice between maybe breaking poorly written
> > monitoring schemes (the lack of a log should merely be a hint to
> > check deeper rather then be the be-all and end-all of ones decision
> > making) and definately breaking the very system that they are meant
> > to monitor.
> 
> I consider this race condition to be minor, since it obviously only
> happens on very heavily loaded systems, which should have a competent

Well not really. It's just more likely to happen on a heavily loaded
system due to the increased number of msgs it processes. It can happen
with any system. It only takes one message to come in at the right time.

> system admin around to isolate the issue. You are always free to

And an on-call monkey who actually gives you a call. :/ As with all
problems that cause tears they're mostlikely to occur when you're
asleep.

> change the configuration yourself, /etc/logrotate.d/exim4-base is a
> dpkg-conffile.

I'm already bulding my own debs for this, which is annoying as I'm not
doing this to add features but to fix some brokenness.

The thing is, there's no need to precreate the logfile (broken
monitoring systems aside) and doing so can break things and has
broken things. I'd say the opposite tact should be taken. If you are
relying on a monitoring system that relies on the logfile always
being there then have it pre-created and deal with the race condition of
the mintor slot where there is no logfile between the move of the old
and the creation of the new.

The priority should be to make sure the things the exim package setup
do not cause exim to die. Other things should take care of themselves.

-- 
    "To the extent that we overreact, we proffer the terrorists the
    greatest tribute."
    	- High Court Judge Michael Kirby