redeployment of openvswitch fails

[Wouter van Bommel]

On an existing cloud a host was reconfigured from sriov (with sriov speficic charm for nova & openvswitch) to a non sriov host.
This fails in the config-changed hook with the following traceback:

2020-03-16 06:19:03 WARNING juju-log Support for use of upstream ``apt_pkg`` module in conjunctionwith charm-helpers is deprecated since 2019-06-25
2020-03-16 06:19:04 DEBUG config-changed Traceback (most recent call last):
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/config-changed", line 266, in <module>
2020-03-16 06:19:04 DEBUG config-changed main()
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/config-changed", line 259, in main
2020-03-16 06:19:04 DEBUG config-changed hooks.execute(sys.argv)
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/charmhelpers/core/hookenv.py", line 914, in execute
2020-03-16 06:19:04 DEBUG config-changed self._hooks[hook_name]()
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/charmhelpers/contrib/openstack/utils.py", line 1568, in wrapped_f
2020-03-16 06:19:04 DEBUG config-changed stopstart, restart_functions)
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/charmhelpers/core/host.py", line 741, in restart_on_change_helper
2020-03-16 06:19:04 DEBUG config-changed r = lambda_f()
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/charmhelpers/contrib/openstack/utils.py", line 1567, in <lambda>
2020-03-16 06:19:04 DEBUG config-changed (lambda: f(*args, **kwargs)), __restart_map_cache['cache'],
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/config-changed", line 149, in config_changed
2020-03-16 06:19:04 DEBUG config-changed configure_ovs()
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/neutron_ovs_utils.py", line 557, in configure_ovs
2020-03-16 06:19:04 DEBUG config-changed modern_ovs = ovs_has_late_dpdk_init()
2020-03-16 06:19:04 DEBUG config-changed File "/var/lib/juju/agents/unit-neutron-openvswitch-15/charm/hooks/neutron_ovs_utils.py", line 802, in ovs_has_late_dpdk_init
2020-03-16 06:19:04 DEBUG config-changed return apt_pkg.version_compare(ovs_version, '2.6.0') >= 0
2020-03-16 06:19:04 DEBUG config-changed TypeError: a bytes-like object is required, not 'NoneType'
2020-03-16 06:19:04 ERROR juju.worker.uniter.operation runhook.go:132 hook "config-changed" failed: exit status 1

The cloud is running 19.10 charm release. Other hosts are running fine with the same charm & config.

[Aurelien Lourot (aurelien-lourot)]

This area has been refactored very recently, so it might be fixed. I'm not sure I precisely understand "a host was reconfigured from sriov to a non sriov host". How was it done? So the physical machine didn't support SR-IOV anymore but the config of the charm still had SR-IOV?

[Andrea Ieri (aieri)]

The detail about sriov is actually not particularly relevant, the important bit is that this bug is triggered when neutron-openvswitch is redeployed a second time to the same machine.

To reproduce:
1. juju deploy nova-compute app1 # let's assume this yields app1/0 on machine 0
2. juju relate neutron-openvswitch app1
3. juju deploy ubuntu --to 0
4. juju remove-unit app1/0 # machine 0 won't be released due to step 3
5. juju deploy nova-compute app2 --to 0
6. juju relate neutron-openvswitch app2