[libvirt] [RFC Incomplete Patch] Libvirt + Openvswitch

[Laine Stump]

On 01/27/2012 05:58 AM, Dan Wendlandt wrote:
> Hello all,
>
> I know of many people who want to spin up VMs using libvirt + kvm/qemu 
> and attach those VMs to an openvswitch bridge (see: 
> http://www.openvswitch.org).   However, the only way I know of to get 
> this working is a kludge that uses to tap devices along with 
> <interface type="ethernet"> while running ovs-vsctl outside of 
> libvirt.  Even worse, doing this on RHEL/Fedora seems to require 
> privilege tweaks (e.g., running qemu as root, not dropping 
> capabilities), which may not be acceptable for production deployments 
> (see: 
> http://fedoraproject.org/wiki/How_to_debug_Virtualization_problems#Errors_using_.3Cinterface_type.3D.27ethernet.27.2F.3E 
> ).
>
> So I would like to start taking steps toward better 
> libvirt/openvswitch integration.  My initial step has the fairly limit 
> goal of enabling kvm/qemu VM NICs to attach to an openvswitch bridge 
> in much the same way VM NIC can already attached to the linux bridge.  
> For example, specifying:
>
> <interface type="openvswitch">
> <source bridge="br0"/>
> <mac address="ca:fe:de;ad:be:ef"/>
> </interface>

It occurred to me while responding to Kyle's post about an openvswitch 
network type that maybe this would be better done as:

<interface type='bridge'>
<source bridge='br0' type='openvswitch'/>
...

This way any management application that hadn't yet been taught about 
the openvswitch extensions would still be able to report useful 
information. This may also make some of the switch statements simpler 
(as well as the change to the NetDef - it would just need an interfaceID 
added to the bridge case of the union). (I made a similar suggestion for 
the network definition as, I see, did Roopa Prabhu, who managed to hit 
send before I did :-)).