Add "also-notifies" option

This patchset adds "also-notifies" option which is an optional part
of the "pools.yaml" configuration and should only be used to define
DNS servers other than the backend servers which should receive
notifications on zone changes.

Change-Id: I10faa6ec4ea4fd1f1f17c7234662cd5c23624c1d
Closes-Bug: 1758008

src/config.yaml

@@ -67,3 +67,10 @@ options:
     type: boolean
     default: false
     description: Enables host request headers.
+  also-notifies:
+    type: string
+    default:
+    description: |
+      Space delimited list of DNS servers which should be notified on every
+      zone change in addition to the backend servers. List is of the form
+      also_notify_ip:also_notify_port

src/lib/charm/openstack/designate.py

@@ -270,6 +270,15 @@ class DesignateConfigurationAdapter(
         """
         return self.nameservers.split()
 
+    @property
+    def also_notifies_hosts(self):
+        also_notifies_hosts = []
+        if hookenv.config('also-notifies'):
+            for entry in hookenv.config('also-notifies').split():
+                address, port = entry.split(':')
+                also_notifies_hosts.append({'address': address, 'port': port})
+        return also_notifies_hosts
+
 
 class DesignateAdapters(openstack_adapters.OpenStackAPIRelationAdapters):
     """

src/templates/mitaka/pools.yaml

@@ -54,16 +54,13 @@
 {% endfor %}
 {% endif %}
 
+{% if options.also_notifies_hosts %}
   also_notifies:
-{% if dns_backend and dns_backend.pool_config %}
-{% for slave in dns_backend.pool_config %}
-    - host: {{ slave.address }}
-      port: 53
-{% endfor %}
-{% endif %}
-{% if options.pool_config %}
-{% for slave in options.pool_config %}
-    - host: {{ slave.address }}
-      port: 53
+{% for also_notify_host in options.also_notifies_hosts %}
+    - host: {{ also_notify_host.address }}
+      port: {{ also_notify_host.port }}
 {% endfor %}
+# Workaround for https://bugs.launchpad.net/designate/+bug/1758013
+{% else %}
+  also_notifies: []
 {% endif %}

unit_tests/test_lib_charm_openstack_designate.py

@@ -194,6 +194,20 @@ class TestDesignateConfigurationAdapter(Helper):
         a = designate.DesignateConfigurationAdapter(relation)
         self.assertEqual(a.rndc_master_ip, 'intip')
 
+    def test_also_notifies_hosts(self):
+        relation = mock.MagicMock
+        test_config = {
+            'also-notifies': '10.0.0.1:53 10.0.0.2:10053',
+        }
+        with mock.patch.object(designate.hookenv, 'config',
+                               side_effect=FakeConfig(test_config)):
+            expect = [{'address': '10.0.0.1',
+                       'port': '53'},
+                      {'address': '10.0.0.2',
+                       'port': '10053'}]
+            a = designate.DesignateConfigurationAdapter(relation)
+            self.assertEqual(a.also_notifies_hosts, expect)
+
 
 class TestDesignateCharm(Helper):