Pass dns-domain over neutron-api relation

In order to have nova-metadata-api use the same dns-domain as neutron
when nova-metadata-api runs on nova-cloud-controller we must pass the
dns-domain on the neutron-api relation.

Change-Id: I14fe163a445b6dcffccced762041942de7d6b41d
Partial-Bug: #1805645
(cherry picked from commit f90eef2c4b)

hooks/neutron_api_hooks.py

@@ -442,6 +442,11 @@ def neutron_api_relation_joined(rid=None):
     else:
         relation_data['neutron-api-ready'] = "no"
 
+    # LP Bug#1805645
+    dns_domain = get_dns_domain()
+    if dns_domain:
+        relation_data['dns-domain'] = dns_domain
+
     relation_set(relation_id=rid, **relation_data)
     # Nova-cc may have grabbed the neutron endpoint so kick identity-service
     # relation to register that its here

unit_tests/test_neutron_api_hooks.py

@@ -390,6 +390,7 @@ class NeutronAPIHooksTests(CharmTestCase):
         self.relation_ids.side_effect = self._fake_relids
         _canonical_url.return_value = host
         self.api_port.return_value = port
+        self.get_dns_domain.return_value = "dnsdomain."
         neutron_url = '%s:%s' % (host, port)
         _relation_data = {
             'enable-sriov': False,
@@ -397,6 +398,7 @@ class NeutronAPIHooksTests(CharmTestCase):
             'neutron-url': neutron_url,
             'neutron-security-groups': 'no',
             'neutron-api-ready': 'no',
+            'dns-domain': 'dnsdomain.',
         }
         self._call_hook('neutron-api-relation-joined')
         self.relation_set.assert_called_with(