[libvirt-users] Starting processes inside VMs using Libvirt?

[Martin Kletzander]

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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