On Thu, Jul 14, 2011 at 05:14:57PM +0200, Michal Novotny wrote:
Hi guys, some time ago I've been investigating the options to get the guest's IP address information without having to connect to guest's VNC window or console. It was for one project I've been working on and I found that the solution lies in the procfs, precisely in the /proc/{PID}/net/arp...
The format is as follows:
$ cat /proc/{PID}/net/arp IP address HW type Flags HW address Mask Device 192.168.122.36 0x1 0x2 52:54:00:35:76:e6 * virbr0
where the HW address matches the MAC address associated to the guest's NIC. Implementing such an API shouldn't be a big problem however I know that there's some option to run libvirt on Windows machines. It should be just the client so it shouldn't really matter however I'd like to ask you whether it's really not an issue.
The function should return a string of the guest's IP address as read from the procfs or return a NULL value if there's no IP address associated with the guest.
If the multiple NICs are being used by the guest then the function should return either the IP address matching the MAC address passed to the function or the first IP address if omitted.
The prototype should be:
char *virDomainGetIPAddress(virDomainPtr domain, char *devmac);
For this the internal information about PID of the process spawned should be used (this is already being tracked and stored by libvirt IMHO) to access the /proc/{PID}/net/arp file.
This API function would be very useful since it would give libvirt users option to get the information of the guest's IP address without having to connect to guest's VNC window or console.
For virsh this could be implemented directly into the dominfo subcommand.
What do you think about implementing this ?
I'm not entirely convinced was want to have this in our APIs, since the arp probing is not really a reliable basis for reporting guest IP details. In the near future there will be guest agents for QEMU which can report this information reliably and I think they're a better bet for any app which would want this information. 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 :|