11:36 a.m.
Hi there,
I am a beginner with Libvirt. I was practicing using Python bindings with
libvirt to do some basic stuff like starting a VM, rebooting a VM,
displaying the number of domain,etc. I was wondering since the hypervisor
has control over the VMs, it is possible to use Libvirt to inject code into
the VM? Is it possible to start processes inside a particular VM using the
Libvirt API. If not, what would you recommend instead? Thanks in advance
Regards,
T.alsaid
12:17 p.m.
On 03/24/2014 10:36 AM, Taimur Al Said wrote:
Hi there,
I am a beginner with Libvirt. I was practicing using Python bindings with
libvirt to do some basic stuff like starting a VM, rebooting a VM,
displaying the number of domain,etc. I was wondering since the hypervisor
has control over the VMs, it is possible to use Libvirt to inject code into
the VM? Is it possible to start processes inside a particular VM using the
Libvirt API. If not, what would you recommend instead? Thanks in advance
What hypervisor are you using? With lxc:// URI, this is already
possible (see virsh lxc-enter-namespace). With qemu:// URI, this isn't
really libvirt's thing to do directly; but you might be able to enhance
the qemu-guest-agent to run an arbitrary command, then install that
agent in your guest, then use libvirt's 'virsh qemu-agent-command' to
drive that new agent command.
If the changes you want in your guest can be done while the guest is
offline, then libguestfs is a great suite of tools for making all sorts
of guest disk image modifications (which is as programmatic as you can
get for injecting behavior changes into your guest). But actually
injecting live processes into a running qemu guest is not possible
without setting up some sort of higher-level protocol, such as
qemu-guest-agent.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
2:31 p.m.
Thank you Eric,
I am using KVM: qemu.. I'll try to see how I can use qemu-guest-agent..
If you have links to examples on how to start with it let me know please.
Consider the following simple scenario..
I am using KVM to run several VMs; one of OSs in the guests is Windows XP.
I want to send to it something from the Hypervisor level, e,g
text,parameters,etc
so that it will be displayed in the VM screen or stored in a file so I can
read from the VM later..
It's best to be done on a live VM.
How can such a simple scenario be performed. Does it have to be through the
method of qemu-guest-agent??
Thanks alot,
T.alsaid
On Mon, Mar 24, 2014 at 5:17 PM, Eric Blake <eblake(a)redhat.com> wrote:
On 03/24/2014 10:36 AM, Taimur Al Said wrote:
> Hi there,
>
> I am a beginner with Libvirt. I was practicing using Python bindings with
> libvirt to do some basic stuff like starting a VM, rebooting a VM,
> displaying the number of domain,etc. I was wondering since the hypervisor
> has control over the VMs, it is possible to use Libvirt to inject code
into
> the VM? Is it possible to start processes inside a particular VM using
the
> Libvirt API. If not, what would you recommend instead? Thanks in advance
What hypervisor are you using? With lxc:// URI, this is already
possible (see virsh lxc-enter-namespace). With qemu:// URI, this isn't
really libvirt's thing to do directly; but you might be able to enhance
the qemu-guest-agent to run an arbitrary command, then install that
agent in your guest, then use libvirt's 'virsh qemu-agent-command' to
drive that new agent command.
If the changes you want in your guest can be done while the guest is
offline, then libguestfs is a great suite of tools for making all sorts
of guest disk image modifications (which is as programmatic as you can
get for injecting behavior changes into your guest). But actually
injecting live processes into a running qemu guest is not possible
without setting up some sort of higher-level protocol, such as
qemu-guest-agent.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
2:36 p.m.
On 03/24/2014 01:31 PM, Taimur Al Said wrote:
Thank you Eric,
[please don't top-post on technical lists]
I am using KVM: qemu.. I'll try to see how I can use qemu-guest-agent..
If you have links to examples on how to start with it let me know please.
Consider the following simple scenario..
I am using KVM to run several VMs; one of OSs in the guests is Windows XP.
I want to send to it something from the Hypervisor level, e,g
text,parameters,etc
so that it will be displayed in the VM screen or stored in a file so I can
read from the VM later..
It's best to be done on a live VM.
Definitely a job for a guest agent. But libvirt doesn't maintain guest
agents - the qemu-guest-agent is part of the qemu project, so you may be
better off asking there.
How can such a simple scenario be performed. Does it have to be through the
method of qemu-guest-agent??
As far as I know, qga does not yet have such a command, so your first
line of attack is to patch the qemu sources to add a new guest agent
command.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
4:14 a.m.
On Mon, Mar 24, 2014 at 01:36:37PM -0600, Eric Blake wrote:
On 03/24/2014 01:31 PM, Taimur Al Said wrote:
> Thank you Eric,
[please don't top-post on technical lists]
>
> I am using KVM: qemu.. I'll try to see how I can use qemu-guest-agent..
> If you have links to examples on how to start with it let me know please.
> Consider the following simple scenario..
>
> I am using KVM to run several VMs; one of OSs in the guests is Windows XP.
> I want to send to it something from the Hypervisor level, e,g
> text,parameters,etc
> so that it will be displayed in the VM screen or stored in a file so I can
> read from the VM later..
> It's best to be done on a live VM.
Definitely a job for a guest agent. But libvirt doesn't maintain guest
agents - the qemu-guest-agent is part of the qemu project, so you may be
better off asking there.
Unless you really just want to setup some initial data in which case
you might use your own initrd and setup things according to
command-line parameters. You would have to use direct kernel boot
though. The other option (if you don't want to change guest agent)
would be to run your own application inside the VM with which you'd be
able to communicate with e.g. virtio-serial to send it the data you
need. Or, probably too overkilling, fetch the data from the VM over
network from some setup server in which this data would be stored
based on UUID of the machine for example.
Martin
>
> How can such a simple scenario be performed. Does it have to be through the
> method of qemu-guest-agent??
As far as I know, qga does not yet have such a command, so your first
line of attack is to patch the qemu sources to add a new guest agent
command.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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