Re: [libvirt] [RFC Incomplete Patch] Libvirt + Openvswitch

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... ). 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> I also wanted to add a new child element of <interface> that can be used to specify some OVS specific configuration. To start, I just want to expose a single 'interfaceid' value (this parameter is specific to openvswitch). Extending the previous example: <interface type="openvswitch"> <source bridge="br0"/> <mac address="ca:fe:de;ad:be:ef"/> <openvswitchport interfaceid="interface-xyz"/> </interface> For this first step (see attached patch), I am only targeting the model where the OVS bridge has been created externally ahead of time. I am not tackling any of the "network" logic that actually creates/destroys bridges, as it is not needed for my target use case. A couple notes about the attached patch: - I haven't actually run this code. I was just poking around the libvirt code to learn about it and figured that a diff was the most concrete way to propose what I was thinking of doing. I would be curious for pointers about big chunks of work that I may have missed (for example, I haven't added any tests yet). - the code was modeled on the network interface "bandwidth" code, that calls out to 'tc' to configure bandwidth rates. Ideally we would be able to make direct C calls to OVS (and we plan to make that possible in the future), but calling an external utility right now is the only viable path. - no attention was paid to style guidelines. Will do that before any real submission. - I wasn't very clear on the notion of an "actual" net def, as opposed to a normal net def. What's the best place to look for documentation on this? Anyway, I'm primarily looking for feedback about whether I'm barking up the right tree before I spend time debugging or polishing the patch, so I would appreciate thoughts, advice, etc. Thanks, Dan