Comment 7 for bug 1826419

I am able to reproduce the bug 1) Forward and reverse resolution is not honoring the network defined dns-domain. -expressed on my previous comment without even having designate enabled on my setup.

Deploying this bundle: http://paste.ubuntu.com/p/FZff5NqfvN/ , with the following neutron config options, please
note that a global.neutron. domain has been configured for neutron.

    options:
      dns-domain: global.neutron.
      enable-ml2-dns: true
      enable-ml2-port-security: true
      flat-network-providers: physnet1
      neutron-security-groups: true
      reverse-dns-lookup: true

Then associating a specific domain (local.neutron) to the private network:

$ neutron net-update --dns-domain local.neutron. private

ubuntu@niedbalski-bastion:~/stsstack-bundles/openstack$ openstack network show private | grep dns_domain
| dns_domain | local.neutron. |

After this step, I launched 3 instances that are associated to this private network.Then if I look into
the --domain attribute of the dnsmasq instance I can see that the configured domain remains as the dns-domain
set for the network.

verifying the --dns-domain option used on the instances network namespace.
root@juju-2e7dc7-1826419-5:/home/ubuntu# ip netns exec qrouter-c5a67f6a-3a15-4dcd-923d-c5c457beddff bash
root@juju-2e7dc7-1826419-5:/home/ubuntu# ps aux|grep dns|grep domain
nobody 491 0.0 0.0 53328 2888 ? S 17:00 0:00 dnsmasq --no-hosts --no-resolv --except-interface=lo --[...]
87/leases --dhcp-match=set:ipxe,175 --bind-interfaces --interface=ns-75130a43-55 --dhcp-range=set:tag0,192.168.21.0,static,255.255.255.0,86400s --dhcp-option-force=option:mtu,1458 --dhcp-lease-max=256 --conf-file=/etc/neutron/dnsmasq.conf --domain=local.neutron.

However, the dhcp host file generated from the dns-assignments are pointing to the global
domain set in neutron-api.

root@juju-2e7dc7-1826419-5:/home/ubuntu# more /var/lib/neutron/dhcp/77902f51-2ac8-4ef1-97d1-962dd745ba87/host

fa:16:3e:d0:80:35,host-192-168-21-1.global.neutron.,192.168.21.1
fa:16:3e:f0:e2:a5,host-192-168-21-2.global.neutron.,192.168.21.2
fa:16:3e:1d:25:6d,cirros-170754-1.global.neutron.,192.168.21.4
fa:16:3e:39:12:a2,cirros-170754-2.global.neutron.,192.168.21.5
fa:16:3e:5b:cd:48,cirros-170754-3.global.neutron.,192.168.21.16

Then if I look at any of the port's dns-assignment they're also pointing to the global.neutron. domain,
not the one defined for the network

ubuntu@niedbalski-bastion:~/stsstack-bundles/openstack$ neutron port-show 75130a43-558e-4b17-90b8-45dc853fbaf7 | grep dns
| dns_assignment | {"hostname": "host-192-168-21-2", "ip_address": "192.168.21.2", "fqdn": "host-192-168-21-2.global.neutron."} |

This port assignment explains the mismatch in the dnsmasq resolution, because this is used for generating
the hosts file used by dnsmasq.

In my opinion rather than reverting this patch, the way to fix this is to adjust the https://github.com/openstack/neutron/blob/c21d922abd1208a72fe64d404a8eab93e0c56870/neutron/plugins/ml2/extensions/dns_integration.py#L287
dns_assignment update to use the network provided dns_name instead of the global configuration.