Where installing OpenStack Icehouse 11 March 2015, I found that I have an issue with nova-compute where it was unable to import libvirt modules as shown below the tail of /var/log/nova/nova-compute.log.

2015-05-25 19:17:12.652 19004 ERROR stevedore.extension [-] Could not load 'file': cannot import name util
2015-05-25 19:17:12.653 19004 ERROR stevedore.extension [-] cannot import name util
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension Traceback (most recent call last):
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension   File "/usr/local/lib/python2.7/dist-packages/stevedore/extension.py", line 162, in _load_plugins
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension     verify_requirements,
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension   File "/usr/local/lib/python2.7/dist-packages/stevedore/extension.py", line 185, in _load_one_plugin
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension     plugin = ep.load(require=verify_requirements)
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension   File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 1989, in load
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension     entry = __import__(self.module_name, globals(),globals(), ['__name__'])
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension   File "/usr/lib/python2.7/dist-packages/nova/image/download/file.py", line 23, in <module>
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension     import nova.virt.libvirt.utils as lv_utils
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/__init__.py", line 15, in <module>
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension     from nova.virt.libvirt import driver
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/driver.py", line 59, in <module>
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension     from eventlet import util as eventlet_util
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension ImportError: cannot import name util
2015-05-25 19:17:12.653 19004 TRACE stevedore.extension
2015-05-25 19:17:12.699 19004 INFO nova.virt.driver [-] Loading compute driver 'libvirt.LibvirtDriver'
2015-05-25 19:17:12.714 19004 ERROR nova.virt.driver [-] Unable to load the virtualization driver
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver Traceback (most recent call last):
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver   File "/usr/lib/python2.7/dist-packages/nova/virt/driver.py", line 1300, in load_compute_driver
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver     virtapi)
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/importutils.py", line 52, in import_object_ns
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver     return import_class(import_str)(*args, **kwargs)
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/importutils.py", line 33, in import_class
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver     traceback.format_exception(*sys.exc_info())))
2015-05-25 19:17:12.714 19004 TRACE nova.virt.driver ImportError: Class LibvirtDriver ...