[libvirt-users] Checking if the VM has been created

[Michal Privoznik]

On 16.11.2011 16:46, William A. Mahaffey III wrote:
> On 11/16/11 08:28, Till Mossakowski wrote:
>> Am 16.11.2011 14:46, schrieb William A. Mahaffey III:
>>
>>> The route command on the host will show the newly added routes for the
>>> VM. Also, tail your syslog file & you will see messages about every 15
>>> min. from dnsmasq w/ the IP adder. of the VM.
>>
>> route just shows the bridge, the individual IP of the VM is only shown
>> in the syslog. However, this is just a workaround, and does not
>> provide reliable identification of the IP if there are many VMs.
>> libvirt resp. virsh should provide a way of obtaining the IP directly
>> from the domain name.
>>
>> Best, Till
>>
>>
> 
> 
> 
> output from 'route -CFvnee' as root on my host attached, 4th line in
> file shows IP addr of my VM, visible in other lines as well ....
> 
> 
> 
> & I definitely agree that virsh *should* show that info :-) ....

It is not so simple. Although we have this 'ip address learning module'
in nwfilters code, it is not reliable. In general there is no reliable
technique to determine guest IP address(es) unless using guest agent
who'll tell us.

Listening on bridge and guessing addresses is not right, as guest might
be not playing a fair game and produce packets with different IP addresses.

Moreover, sniffing on multiple bridges and guessing IP addresses can be
CPU consuming. And one would need to do this sniffing repeatedly as IP
address might change over time.

Michal