how to use python-guestfs to access rbd device? The function i found is g.add_drive_opts, but i dono know how it receive ceph's configuration. 
I found this link
http://rwmj.wordpress.com/2013/03/12/accessing-ceph-rbd-sheepdog-etc-using-libguestfs/

Is that the only way i should use to access ceph rbd? Can we use python-guestfs to get the same effect?
Thanks