Comment 12 for bug 1257644

We can probably take the libvirt _close_connection callback out of the equation here since we're running with libvirt 0.9.8:

"Setting up libvirt0 (0.9.8-2ubuntu17.16) ..."

And the registerCloseCallback is in version >= 1.0.1, so that can't be the problem.

That leaves the finally block in _get_connection added here:

https://review.openstack.org/#/c/52189/9/nova/virt/libvirt/driver.py

So in that case wrapped_conn would have to be None which makes bool(None) result in False and that would disable the service. The nasty thing about that is the disabled_reason is set to '' so we don't even know that we had an automatic disable of the host, which is what change Ia7544a35 was trying to address.