[Libguestfs] Using libguestfs to sandbox VM builds

Hi Debian has a couple of tools like fai-diskimage and vmdebootstrap, to build VM images, but they require being root, as these loopmounts partitions on which deboostrap is executed. Maybe installing grub2 needs access to block devices too. I was thinking of using libguestfs to sandbox those processes, by passing a build VM as a disk image and my build directory as a 9pfs mount to the appliance, and calling the build command via $g->shell(). Any pitfalls I should be aware while doing this ? Emmanuel