Re: [Qemu-devel] [libvirt-users] Using virsh to load scripts for the guest machine

Re: [Qemu-devel] [libvirt-users] Using virsh to load scripts for the guest machine

[Eric Blake]

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On 07/30/2012 12:00 PM, Mauricio Tavares wrote:
> On Mon, Jul 30, 2012 at 1:50 PM, Eric Blake <eblake@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@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [libvirt-users] Using virsh to load scripts for the guest machine

[Anthony Liguori]

Eric Blake <eblake@redhat.com> writes:

> On 07/30/2012 12:00 PM, Mauricio Tavares wrote:
>> On Mon, Jul 30, 2012 at 1:50 PM, Eric Blake <eblake@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.

Could you setup a wiki page on qemu.org with a list of qemu-ga
commands that libvirt would like?

Adding commands is pretty trivial so if ya'll have a list of things
you'd like, they're great quick tasks that we can find folks to work on.

Regards,

Anthony Liguori

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

Re: [Qemu-devel] [libvirt-users] Using virsh to load scripts for the guest machine

[Eric Blake]

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On 08/01/2012 07:48 AM, Anthony Liguori wrote:
>>>       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.
> 
> Could you setup a wiki page on qemu.org with a list of qemu-ga
> commands that libvirt would like?

I gave it a shot (feel free to improve it)
http://wiki.qemu.org/Features/GuestAgent/UsefulCommands

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


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