When trying to add the relation between nova-cloud-controller and nova-compute, I came accross this situation:
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed Traceback (most recent call last):
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/hooks/cloud-compute-relation-changed", line 1383, in <module>
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed main()
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/hooks/cloud-compute-relation-changed", line 1375, in main
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed hooks.execute(sys.argv)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/charmhelpers/core/hookenv.py", line 945, in execute
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed self._hooks[hook_name]()
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/hooks/cloud-compute-relation-changed", line 676, in cloud_compute_relation_changed
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed update_ssh_keys_and_notify_compute_units(rid=None, unit=None)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/hooks/cloud-compute-relation-changed", line 721, in update_ssh_keys_and_notify_compute_units
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed update_ssh_key(rid=rid, unit=unit)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/hooks/cloud-compute-relation-changed", line 834, in update_ssh_key
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed resolved_hosts = ncc_utils.resolve_hosts_for(private_address, hostname)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/hooks/nova_cc_utils.py", line 1348, in resolve_hosts_for
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed hn = ch_utils.get_hostname(private_address)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/charmhelpers/contrib/network/ip.py", line 522, in get_hostname
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed result = ns_query(rev)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/var/lib/juju/agents/unit-nova-cloud-controller-6/charm/charmhelpers/contrib/network/ip.py", line 478, in ns_query
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed answers = dns.resolver.query(address, rtype)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/usr/lib/python3/dist-packages/dns/resolver.py", line 1132, in query
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed raise_on_no_answer, source_port)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed File "/usr/lib/python3/dist-packages/dns/resolver.py", line 947, in query
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed raise NoNameservers(request=request, errors=errors)
unit-nova-cloud-controller-6: 16:36:03 DEBUG unit.nova-cloud-controller/6.cloud-compute-relation-changed dns.resolver.NoNameservers: All nameservers failed to answer the query 13.4.16.172.in-addr.arpa. IN PTR: Server 127.0.0.53 UDP port 53 answered SERVFAIL
unit-nova-cloud-controller-6: 16:36:03 ERROR juju.worker.uniter.operation hook "cloud-compute-relation-changed" (via explicit, bespoke hook script) failed: exit status 1
Every other relation works, except for this one. The DNS search domain are well set up. I've added the "search: [maas]" command in the 50-cloud-init.yaml and it is present in every systemd-resolve status and 99-juju.yaml files, but it wont fix it.