libvirt users - Jun 2020 - Re: Is it possible to configure libvirt's MAC generation?

On 6/12/20 12:28 PM, Peter Crowther wrote:
> Specify the MAC address as part of the domain XML for the bootstrap 
> node.  See https://libvirt.org/formatdomain.html#elementsNICS.
Unfortunately, the domain XML is created by the OpenShift installer,
over which I have no control.  :-(

Digging into the libvirt source, it doesn't look like there's any way
to configure MAC address generation.  I'm now investigating whether I
can mangle the source MAC of the outgoing DHCP packets with ebtables.

Uugh.

-- 
=======================================================================         
In Soviet Russia, Google searches you!
========================================================================

One solution would be to dump the XML for the domain and then run 
something like sed on it to change what ever you want and then update 
the domain.
Of course that will only work if the domain is stopped.

On 6/12/20 2:00 PM, Ian Pilcher wrote:
> On 6/12/20 12:28 PM, Peter Crowther wrote:
>> Specify the MAC address as part of the domain XML for the bootstrap 
>> node.  See https://libvirt.org/formatdomain.html#elementsNICS.
>
> Unfortunately, the domain XML is created by the OpenShift installer,
> over which I have no control.  :-(
>
> Digging into the libvirt source, it doesn't look like there's any
way
> to configure MAC address generation.  I'm now investigating whether I
> can mangle the source MAC of the outgoing DHCP packets with ebtables.
>
> Uugh.
>
-- 
Alvin Starr                   ||   land:  (647)478-6285
Netvel Inc.                   ||   Cell:  (416)806-0133
alvin@netvel.net              ||

>======================================================================>  
In Soviet Russia, Google searches you!
>======================================================================
You can easily remove 'In Soviet Russia, '

On Fri, Jun 12, 2020 at 02:18:13PM -0400, Alvin Starr
wrote:
> One solution would be to dump the XML for the domain and then run something
> like sed on it to change what ever you want and then update the domain.
> Of course that will only work if the domain is stopped.
Another one is to use the virt-xml tool to update only the part you need:

virt-xml <domain> --edit --network
network=default,mac.address='<new_mac>'

^This would require you to restart the domain for the change to take effect.

virt-xml <domain> --update --remove device --network
mac.address='<old_mac>'
virt-xml <domain --update --add-device --network
network=default,mac.address='<new_mac>'

^This would not, because it translates to hot-unplug and hot-plug respectively.

Just an alternative to using sed.

Regards,
Erik