Restart nova-api-metadata on restart_nonce changes

The nova-cloud-controller presents a restart_nonce key on the
quantum-network-service relation once db migration has been
completed and the nova-conductor service is able to respond to
RPC calls.

Restart the nova-api-metadata when this data changes to ensure
a running service post deployment.

Change-Id: Iafc27fbb2a70e3195fc189e4056a1ca58ff6b663
Closes-Bug: 1547122

.gitignore

@@ -10,3 +10,4 @@ precise
 trusty
 wily
 xenial
+.unit-state.db

hooks/neutron_hooks.py

@@ -12,6 +12,8 @@ from charmhelpers.core.hookenv import (
     UnregisteredHookError,
     status_set,
 )
+from charmhelpers.core.host import service_restart
+from charmhelpers.core.unitdata import kv
 from charmhelpers.fetch import (
     apt_update,
     apt_install,
@@ -34,6 +36,7 @@ from charmhelpers.contrib.openstack.utils import (
     openstack_upgrade_available,
     os_requires_version,
     pausable_restart_on_change as restart_on_change,
+    is_unit_paused_set,
 )
 from charmhelpers.payload.execd import execd_preinstall
 from charmhelpers.core.sysctl import create as create_sysctl
@@ -220,6 +223,20 @@ def nm_changed():
     if config('ha-legacy-mode'):
         cache_env_data()
 
+    # NOTE: nova-api-metadata needs to be restarted
+    #       once the nova-conductor is up and running
+    #       on the nova-cc units.
+    restart_nonce = relation_get('restart_nonce')
+    if restart_nonce is not None:
+        db = kv()
+        previous_nonce = db.get('restart_nonce',
+                                restart_nonce)
+        if previous_nonce != restart_nonce:
+            if not is_unit_paused_set():
+                service_restart('nova-api-metadata')
+            db.set('restart_nonce', restart_nonce)
+            db.flush()
+
 
 @hooks.hook("cluster-relation-departed")
 @restart_on_change(restart_map())

unit_tests/test_neutron_hooks.py

@@ -54,6 +54,9 @@ TO_PATCH = [
     'cleanup_ovs_netns',
     'stop_neutron_ha_monitor_daemon',
     'use_l3ha',
+    'kv',
+    'service_restart',
+    'is_unit_paused_set',
 ]
 
 
@@ -277,11 +280,60 @@ class TestQuantumHooks(CharmTestCase):
         self.assertTrue(self.CONFIGS.write_all.called)
 
     def test_nm_changed(self):
-        self.relation_get.return_value = "cert"
+        def _relation_get(key):
+            data = {
+                'ca_cert': 'cert',
+                'restart_nonce': None,
+            }
+            return data.get(key)
+        self.relation_get.side_effect = _relation_get
         self._call_hook('quantum-network-service-relation-changed')
         self.assertTrue(self.CONFIGS.write_all.called)
         self.install_ca_cert.assert_called_with('cert')
 
+    def test_nm_changed_restart_nonce_changed(self):
+        def _relation_get(key):
+            data = {
+                'ca_cert': 'cert',
+                'restart_nonce': '1111111222222333333',
+            }
+            return data.get(key)
+        self.relation_get.side_effect = _relation_get
+        self.is_unit_paused_set.return_value = False
+        kv_mock = MagicMock()
+        self.kv.return_value = kv_mock
+        kv_mock.get.return_value = ('22222233333344444')
+        self._call_hook('quantum-network-service-relation-changed')
+        self.assertTrue(self.CONFIGS.write_all.called)
+        self.install_ca_cert.assert_called_with('cert')
+        self.service_restart.assert_called_with('nova-api-metadata')
+        kv_mock.get.assert_called_with('restart_nonce',
+                                       '1111111222222333333')
+        kv_mock.set.assert_called_with('restart_nonce',
+                                       '1111111222222333333')
+        self.assertTrue(kv_mock.flush.called)
+
+    def test_nm_changed_restart_nonce_nochange(self):
+        def _relation_get(key):
+            data = {
+                'ca_cert': 'cert',
+                'restart_nonce': '1111111222222333333',
+            }
+            return data.get(key)
+        self.relation_get.side_effect = _relation_get
+        self.is_unit_paused_set.return_value = False
+        kv_mock = MagicMock()
+        self.kv.return_value = kv_mock
+        kv_mock.get.return_value = ('1111111222222333333')
+        self._call_hook('quantum-network-service-relation-changed')
+        self.assertTrue(self.CONFIGS.write_all.called)
+        self.install_ca_cert.assert_called_with('cert')
+        self.assertFalse(self.service_restart.called)
+        kv_mock.get.assert_called_with('restart_nonce',
+                                       '1111111222222333333')
+        self.assertFalse(kv_mock.set.called)
+        self.assertFalse(kv_mock.flush.called)
+
     def test_neutron_plugin_changed(self):
         self.use_l3ha.return_value = True
         self._call_hook('neutron-plugin-api-relation-changed')