nspawn_cache_prep_dns only works on initial container image creation

[Marcus Klein]

I would like to overwrite the default DNS nameservers used for the nspawn container setup. We use an internal Ubuntu mirror, which can only be resolved by our internal DNS servers and not by
208.67.222.222 and 8.8.8.8.

When running

openstack-ansible setup-hosts.yml

my configured DNS are only properly configured in the Ubuntu container image ubuntu-bionic-amd64 when the container image does not exist. If it exists the default DNS servers are configured and the following container image setup command fails

fatal: [controller1]: FAILED! => {"changed": false, "cmd": "chroot /var/lib/machines/ubuntu-bionic-amd64 /usr/local/bin/cache-prep-commands.sh > /var/log/nspawn-cache-prep-commands.log 2>&1", "delta": "0:00:00.970962", "end": "2019-05-31 12:21:10.374885", "msg": "non-zero return code", "rc": 100, "start": "2019-05-31 12:21:09.403923", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}

It is not very convenient to have to delete the base container image when setting up some nspawn container.

[Jonathan Rosser (jrosser)]

support for nspawn has been removed from currently supported versions of openstack-ansible