Libguestfs - Aug 2009 - Can I use libguestfs to pass some parameters into a KVM virtual machine

Hi,

I have installed KVM in my RHEL5.3 box, and created some VMs on it.
I am wondering if I can use libguestfs to pass some parameters/files
into my VMs. As you may know, for Xen, I can use xenstore command to
do this job, can libguestfs do the same thing?

What I want to do includes:
1. Modify some configurations in my VM, such as editing
/etc/sysconfig/network-scripts/ifcfg-eth0 to add a static IP for my
VM.
2. Upload a script into my VM and run it in the guest OS.

Is here any sample C code I can refer to?

Any helps will be appreciated, thanks!


Regards,
Qian

Zhang Qian wrote:
> I have installed KVM in my RHEL5.3 box, and created some VMs on it.
> I am wondering if I can use libguestfs to pass some parameters/files
> into my VMs.
Yup, that's pretty much exactly what libguestfs is good for -- though, 
not being familiar with xenstore, let me add that the VMs need to be 
down before you try to modify their filesystems.

I suggest scripting what you're trying to do with guestfish before going 
on to the C API -- it's pretty easy to look at how any guestfish command 
is implemented in C, and so to do what you want natively if that's your 
inclination.

On Tue, Aug 04, 2009 at 09:26:31AM +0800, Zhang Qian
wrote:
> I have installed KVM in my RHEL5.3 box, and created some VMs on it.
> I am wondering if I can use libguestfs to pass some parameters/files
> into my VMs. As you may know, for Xen, I can use xenstore command to
> do this job, can libguestfs do the same thing?
> 
> What I want to do includes:
> 1. Modify some configurations in my VM, such as editing
> /etc/sysconfig/network-scripts/ifcfg-eth0 to add a static IP for my
> VM.
> 2. Upload a script into my VM and run it in the guest OS.
Yes, this is precisely what libguestfs is for.  Make sure the virtual
machine is shut down before you try to modify it.
> Is here any sample C code I can refer to?
There are some very simple examples in the source:

  http://git.et.redhat.com/?p=libguestfs.git;a=tree;f=examples;hb=HEAD

And the documentation of the C API:

  http://libguestfs.org/guestfs.3.html

See in particular:

  http://libguestfs.org/guestfs.3.html#uploading
  http://libguestfs.org/guestfs.3.html#running_commands

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v