[libvirt] libvirt/dnsmasq integration.

[Daniel P. Berrange]

On Wed, Feb 24, 2010 at 04:37:04PM +0000, Simon Kelley wrote:
> Richard W.M. Jones wrote:
> > On Wed, Feb 24, 2010 at 02:34:53PM +0000, Simon Kelley wrote:
> > [...]
> >> Does that make sense? It's a long and involved explanation to come to  
> >> cold. I fear I may have over-simplified what libvirt is doing with  
> >> dnsmasq, in which case please enlighten me and I'll modify my scheme to  
> >> take that into account. If this looks good I can easily have the  
> >> necessary dnsmasq changes in the next release.
> > 
> > I read through it and it makes sense to me.
> > 
> > The only thing: is /etc/dnsmasq.d a true standard across all distros?
> > It is for Fedora, but an old Debian distro I use does not have this
> > directory.
> 
> The ability to read config fragments from a directory has been in
> dnsmasq since version 2.32 (effectively, forever). The Debian (and by
> inheritance, Ubuntu) packages have created and automatically searched
> /etc/dnsmasq.d since 2.46, released in November 2008. That's not quite
> old enough to be in the current Debian stable, which has 2.45.
> 
> All this is slighly moot, since this scheme needs changes to dnsmasq.
> Those can easily go into the next release.
> 
> > 
> > Is '/etc/init.d/dnsmasq restart' a reliable way to restart the system
> > dnsmasq across all distros?  (Perhaps 'service dnsmasq restart' is
> > better?).
> 
> Almost certainly. Could this be a hook supplied by the distro packaging?

I'm not sure that the 'service' command is standardized on all distros
either, is it ? 

Does dnsmasq need a full restart, or is a SIGHUP sufficient ?

If the latter, then we could avoid the initscript entirely, by reading
dnsmasq's pid file, using kill(0, $PID) and check for -ERSCH to see if it
is running or not.  Then finally SIGHUP it to reload


Daniel
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