For Nova in Kilo as of "2015.1.dev672" the system package "python-guestfs" which brings in "libguestfs0" is required. While we may be able to get around requiring in later releases, as this looks like it may be an issue with the dev release of Nova for Kilo, it did not function in fallback mode at all. Without that package installed this was the error:
-- stacktrace --
2015-03-05 04:21:11.003 12875 INFO nova.virt.disk.vfs.api [req-9ded04fa-52dd-4814-8d72-7c57e7b309ab - - - - -] Unable to import guestfs, falling back to VFSLocalFS
2015-03-05 04:21:11.164 12875 ERROR nova.compute.manager [req-9ded04fa-52dd-4814-8d72-7c57e7b309ab - - - - -] [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] Instance failed to spawn
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] Traceback (most recent call last):
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 2301, in _build_resources
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] yield resources
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/compute/manager.py", line 2171, in _build_and_run_instance
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] flavor=flavor)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2349, in spawn
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] admin_pass=admin_password)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 2750, in _create_image
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] instance, size, fallback_from_host)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 5836, in _try_fetch_image_cache
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] size=size)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 230, in cache
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] *args, **kwargs)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 507, in create_image
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] copy_qcow2_image(base, self.path, size)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py", line 431, in inner
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] return f(*args, **kwargs)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/libvirt/imagebackend.py", line 473, in copy_qcow2_image
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] disk.extend(target, size, use_cow=True)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/disk/api.py", line 183, in extend
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] if not is_image_extendable(image, use_cow):
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/disk/api.py", line 235, in is_image_extendable
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] if fs.get_image_fs() in SUPPORTED_FS_TO_EXTEND:
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/virt/disk/vfs/localfs.py", line 167, in get_image_fs
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] run_as_root=True)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/nova/utils.py", line 199, in execute
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] return processutils.execute(*cmd, **kwargs)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] File "/usr/local/lib/python2.7/dist-packages/oslo_concurrency/processutils.py", line 233, in execute
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] cmd=sanitized_cmd)
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] ProcessExecutionError: Unexpected error while running command.
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] Command: sudo nova-rootwrap /etc/nova/rootwrap.conf blkid -o value -s TYPE /dev/nbd2
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] Exit code: 2
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] Stdout: u''
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c] Stderr: u''
2015-03-05 04:21:11.164 12875 TRACE nova.compute.manager [instance: cc067af9-fcdf-4214-9ad7-c3d94176fc9c]
Fix proposed to branch: master /review. openstack. org/166986
Review: https:/