[libvirt] [RFC] The Quest for Domain-IP Mapping Continues...

[Daniel P. Berrange]

On Fri, Dec 05, 2014 at 04:28:10PM +0530, Nehal J Wani wrote:
> On Fri, Dec 5, 2014 at 3:33 PM, Daniel P. Berrange <berrange at redhat.com> wrote:
> > On Fri, Dec 05, 2014 at 12:20:03AM +0530, Nehal J Wani wrote:
> >> If you remember correctly, about 1.2 years ago, we had...
> >> https://www.redhat.com/archives/libvir-list/2013-September/msg00351.html
> >>
> >> In short, the patch proposed a generalized mechanism for finding out
> >> IP addresses, with flags for choosing method(s) (SNOOP|LEASE|AGENT).
> >>
> >> But since not all methods were supported (only qemu-ga worked), the
> >> API was deferred.
> >>
> >> After exploring a bit, it seems that in all, we can have:
> >> (i) Leases Method
> >> (ii) Qemu Guest Agent
> >> (iiI) DHCP Snooping (exists, but isn't publicly exposed?)
> >> (iv) ARP Snooping (we can ask the virtual network interfaces to share
> >> their arp tables with the public?)
> >>
> >> Now that we have the dhcp-leases API fully furnished, why not visit
> >> the qemu-guest-agent again?
> >>
> >> OP1. Should we have separate APIs + virsh commands for each one of
> >> these and then combine them together under
> >> virDomainInterfaceAddresses?
> >> - If each one has to be a different API and then combined later, then
> >> what should be the corresponding name for the virsh command for
> >> exposing the querying guest agent API?
> >> OP2. Implement virDomainInterfaceAddresses API with two flags, one for
> >> dhcp-leases and another for qemu-ga and keep adding others whenever
> >> they are completed?
> >
> > I don't see any real reason to have separate APIs for each method.
> > The API signature will be the same in all cases, so having a single
> > virDomainGetInterfaceAddrs() method with a bunch of flags to control
> > what data source is used is preferrable. I'd expect the DHCP leases
> > method to be used as the default, since that's the most likely method
> > to succeed in the common case.
> 
> So, should I go ahead and redo that patch, with two flags enabled?

I think yuou should redo that patch series adding the DHCP lease support,
since that's the reason we didn't merge that code last time around.

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|