Re: [libvirt] libguestfs integration: rich disk access for libvirt applications
On Wed, Sep 28, 2011 at 06:37:17PM +0100, Daniel P. Berrange wrote:
We do have a historical syntax from Xen paravirt which lets us call
out
to a helper at boot time, namely the "<bootloader>" element. With Xen
this is typically something like pygrub, or pxegrub, which does some
work and writes out a kernel+initrd into temporary files, and prints
the file paths + any kernel args on stdout.
We could just wire up this concept in KVM too without any real trouble,
and then we could have guestfs-bootloader script todo the magic setup
The attached scripts show how it would work, and furthermore they show
that it really does work.
The first script is the bootloader script. This creates the
libguestfs appliance (3 files called /tmp/kernel, /tmp/initrd and
/tmp/root). At the moment, no caching of the appliance is
implemented, but that is easy to add.
The second script shows the sort of changes we would make to the
guestfs_add_domain API in order to run the appliance from libvirt.
It's a Ruby script that creates a transient domain, booting from the
appliance created in step 1, with the correct virtio-serial port etc.
It then tells libguestfs to connect to the virtio-serial socket.
Finally it issues some libguestfs commands to create a filesystem, so
you can tell that it is actually talking to the libguestfs daemon.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
Attachments:
- create.rb (text/plain — 2.5 KB)
- bootstrap.ksh (text/plain — 263 bytes)