nova fails with error: 'module' object has no attribute 'VIR_MIGRATE_POSTCOPY' after using libvirt 2.5.0 from UCA

[Sam Wan]

commit https://review.openstack.org/#/c/451492/ uses libvirt 2.5.0 from UCA, and nova fails with below errors with this change.
===
2017-04-13 19:17:26.927 9868 DEBUG oslo_service.service [req-93d359eb-0146-49ff-aeca-48114f30793a - -] logging_exception_prefix = %(asctime)s.%(msecs)03d %(process)d ERROR %(name)s %(instance)s log_opt_values /usr/local/lib/python2.7/dist-packages/oslo_config/cfg.py:2778
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service [-] Error starting thread.
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service Traceback (most recent call last):
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service File "/usr/local/lib/python2.7/dist-packages/oslo_service/service.py", line 721, in run_service
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service service.start()
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service File "/opt/stack/new/nova/nova/service.py", line 144, in start
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service self.manager.init_host()
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service File "/opt/stack/new/nova/nova/compute/manager.py", line 1135, in init_host
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service self.driver.init_host(host=self.host)
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service File "/opt/stack/new/nova/nova/virt/libvirt/driver.py", line 471, in init_host
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service self._parse_migration_flags()
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service File "/opt/stack/new/nova/nova/virt/libvirt/driver.py", line 629, in _parse_migration_flags
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service live_migration_flags)
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service File "/opt/stack/new/nova/nova/virt/libvirt/driver.py", line 606, in _handle_live_migration_auto_converge
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service (migration_flags & libvirt.VIR_MIGRATE_POSTCOPY) != 0):
2017-04-13 19:17:27.302 9868 ERROR oslo_service.service AttributeError: 'module' object has no attribute 'VIR_MIGRATE_POSTCOPY'
====

some example logs:

http://openstack-ci.tintri.com/tintri/refs-changes-78-455878-2/logs/screen-n-cpu.log.txt
http://publiclogs.emc.com/vnx_ostack/EMC_VNX_iSCSI/371/logs/screen-n-cpu.txt.gz

[Sam Wan (sam-wan)]

It turns out to be some issue with local cached libvirt-python.

devstack uses 'sudo -H' to install pip package
------
./inc/python: local sudo_pip="sudo -H"
------

with '-H', pip will try to use the local cached version. In this case, it uses /root/.cache/pip/
Somehow for this case, there's something wrong with local cached version.
------
~> sudo -H http_proxy= https_proxy= no_proxy= PIP_FIND_LINKS= SETUPTOOLS_SYS_PATH_TECHNIQUE=rewrite /usr/local/bin/pip2.7 install -c /opt/stack/new/requirements/upper-constraints.txt 'libvirt-python>=1.2.5' 2>/dev/null
Collecting libvirt-python===3.2.0 (from -c /opt/stack/new/requirements/upper-constraints.txt (line 224))
Installing collected packages: libvirt-python
Successfully installed libvirt-python-3.2.0
sam@cdh3h6:~> python -c 'import libvirt;libvirt.VIR_MIGRATE_POSTCOPY'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
AttributeError: 'module' object has no attribute 'VIR_MIGRATE_POSTCOPY'
~>
------

but if we tell pip to disable the cache with '--no-cache-dir', we won't run into this issue.
------
~> sudo -H http_proxy= https_proxy= no_proxy= PIP_FIND_LINKS= SETUPTOOLS_SYS_PATH_TECHNIQUE=rewrite /usr/local/bin/pip2.7 install --no-cache-dir -c /opt/stack/new/requirements/upper-constraints.txt 'libvirt-python>=1.2.5' 2>/dev/null
Collecting libvirt-python===3.2.0 (from -c /opt/stack/new/requirements/upper-constraints.txt (line 224))
  Downloading libvirt-python-3.2.0.tar.gz (174kB)
    100% |################################| 184kB 324kB/s
Installing collected packages: libvirt-python
  Running setup.py install for libvirt-python ... done
Successfully installed libvirt-python-3.2.0
~> python -c 'import libvirt;libvirt.VIR_MIGRATE_POSTCOPY'
------

would suggest to disable the cable when devstack install pip packages.

[Sam Wan (sam-wan)]

https://review.openstack.org/#/c/456868/

[Juan Pedro Paredes (juampe)]

This solved the problem for me
pip install libvirt-python==3.2.0