the host libvirtd is disabled on all systems.

So I moved to using ubuntu container images and made some progress. The new error was:

2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [req-2314ed5f-cdb5-4eb5-bd6a-81465d9c77e9 303faf5ba7e14dfda39359834017141e 4b0d0861bbd74771ae693119c5c7265d - default default] [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd] Instance failed to spawn: libvirt.libvirtError: internal error: process exited while connecting to monitor: Could not access KVM kernel module: Permission denied
2019-11-18T18:04:53.369564Z qemu-system-x86_64: failed to initialize KVM: Permission denied
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd] Traceback (most recent call last):
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/compute/manager.py", line 2546, in _build_resources
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     yield resources
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/compute/manager.py", line 2322, in _build_and_run_instance
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     block_device_info=block_device_info)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 3474, in spawn
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     power_on=power_on)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 6251, in _create_domain_and_network
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     destroy_disks_on_failure)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     self.force_reraise()
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     six.reraise(self.type_, self.value, self.tb)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/six.py", line 693, in reraise
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     raise value
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 6220, in _create_domain_and_network
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     post_xml_callback=post_xml_callback)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 6154, in _create_domain
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     guest.launch(pause=pause)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/virt/libvirt/guest.py", line 143, in launch
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     self._encoded_xml, errors='ignore')
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     self.force_reraise()
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     six.reraise(self.type_, self.value, self.tb)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/six.py", line 693, in reraise
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     raise value
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/nova/virt/libvirt/guest.py", line 138, in launch
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     return self._domain.createWithFlags(flags)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 190, in doit
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     result = proxy_call(self._autowrap, f, *args, **kwargs)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 148, in proxy_call
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     rv = execute(f, *args, **kwargs)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 129, in execute
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     six.reraise(c, e, tb)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/six.py", line 693, in reraise
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     raise value
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 83, in tworker
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     rv = meth(*args, **kwargs)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]   File "/usr/lib/python3/dist-packages/libvirt.py", line 1110, in createWithFlags
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd]     if ret == -1: raise libvirtError ('virDomainCreateWithFlags() failed', dom=self)
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd] libvirt.libvirtError: internal error: process exited while connecting to monitor: Could not access KVM kernel module: Permission denied
2019-11-18 11:04:54.152 6 ERROR nova.compute.manager [instance: 7582bd31-4f2e-4832-8036-efee02c1b0fd] 2019-11-18T18:04:53.369564Z qemu-system-x86_64: failed to initialize KVM: Permission denied

I updates /lib/udev/rules.d/60-qemu-system-common.rules from:
KERNEL=="kvm", GROUP="kvm", MODE="0660"
to
KERNEL=="kvm", GROUP="kvm", MODE="0666"
and so far no more errors. I've launched one test machine without issue.