[libvirt-users] Using virsh to load scripts for the guest machine

[Eric Blake]

On 07/30/2012 12:00 PM, Mauricio Tavares wrote:
> On Mon, Jul 30, 2012 at 1:50 PM, Eric Blake <eblake at redhat.com> wrote:
>> On 07/15/2012 07:52 PM, Mauricio Tavares wrote:
>>>     Right on the top of
>>> http://www.centos.org/docs/5/html/5.2/Virtualization/chap-Virtualization-Managing_guests_with_virsh.html,
>>> it seems to imply you can load/send scripts to the vm guest using virsh.
>>> Is that possible? How and what are the limitations? Can you query the vm
>>> guest?
>>
>> What type of scripts are you talking about?  You may be thinking more
>> about the capabilities of what libguestfs provides, for modifying disk
>> images.  In general, virsh itself controls how to start a guest, but not
>> the additional layers of communication (such as virtio, qemu-ga, or the
>> libguestfs appliance app) required for a host to command a guest to do
>> something from within the guest.
>>
>       Basic one would be in case a machine has been paused for a long
> time. You know as in "hey, you lazy vm! You have been sleeping for two
> weeks! Now your clock is way off and poor ntp can't sync it back. So,
> here's current date!"

That is something that fits better through qemu-ga, but no one has
implemented it yet (cc'ing qemu-devel in case I'm misrepresenting
things).  Of course, if we did have a qemu-ga command for pushing the
current time into the guest, then libvirt could usefully expose an API
to wrap that qemu-ga command.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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