[libvirt] how to get started with libvirt & central access control

[Juan Miscaro]

Quite new to libvirt (and kvm).  I played with a few vm's with
libvirt/kvm and vnc/virsh/virt-manager.  I would now like to implement
access control for my vm's (of any format: xen, kvm, etc) to a remote
backend (mysql/ldap/other).  Where does one begin?  I would later want
to do the same but in the context of a cluster of hosts (each running
multiple vm's).  Thanks in advance for any advice.

/juan