Restart services when trigger from principle

Check to see if a restart trigger has been sent by the principle,
if it has then right the trigger uuid in to the neutron.conf to
trigger a service restart

Change-Id: I19649cb73dad94f4fe24412c0b8c37a28f30047d
Partial-Bug: 1571634

hooks/neutron_ovs_context.py

@@ -251,6 +251,20 @@ class SharedSecretContext(OSContextGenerator):
         return ctxt
 
 
+class RemoteRestartContext(OSContextGenerator):
+
+    def __call__(self):
+        for rid in relation_ids('neutron-plugin'):
+            for unit in related_units(rid):
+                restart_uuid = relation_get(
+                    attribute='restart-trigger',
+                    rid=rid,
+                    unit=unit)
+                if restart_uuid:
+                    return {'restart_trigger': restart_uuid}
+        return {}
+
+
 class APIIdentityServiceContext(context.IdentityServiceContext):
 
     def __init__(self):

hooks/neutron_ovs_utils.py

@@ -114,6 +114,7 @@ BASE_RESOURCE_MAP = OrderedDict([
     (NEUTRON_CONF, {
         'services': ['neutron-plugin-openvswitch-agent'],
         'contexts': [neutron_ovs_context.OVSPluginContext(),
+                     neutron_ovs_context.RemoteRestartContext(),
                      context.AMQPContext(ssl_dir=NEUTRON_CONF_DIR),
                      context.ZeroMQContext(),
                      context.NotificationDriverContext()],

templates/kilo/neutron.conf

@@ -3,6 +3,7 @@
 # [ WARNING ]
 # Configuration file maintained by Juju. Local changes may be overwritten.
 # Config managed by neutron-openvswitch charm
+# Service restart triggered by principle using key: {{ restart_trigger }}
 ###############################################################################
 [DEFAULT]
 verbose = {{ verbose }}

unit_tests/test_neutron_ovs_context.py

@@ -13,6 +13,9 @@ TO_PATCH = [
     'network_get_primary_address',
     'glob',
     'PCINetDevices',
+    'relation_ids',
+    'relation_get',
+    'related_units',
 ]
 
 
@@ -464,3 +467,26 @@ class TestDPDKDeviceContext(CharmTestCase):
             'driver': 'uio_pci_generic'
         })
         self.config.assert_called_with('dpdk-driver')
+
+
+class TestRemoteRestartContext(CharmTestCase):
+
+    def setUp(self):
+        super(TestRemoteRestartContext, self).setUp(context,
+                                                    TO_PATCH)
+        self.config.side_effect = self.test_config.get
+
+    def test_restart_trigger_present(self):
+        self.relation_ids.return_value = ['rid1']
+        self.related_units.return_value = ['nova-compute/0']
+        self.relation_get.return_value = '8f73-f3adb96a90d8'
+        self.assertEquals(
+            context.RemoteRestartContext()(),
+            {'restart_trigger': '8f73-f3adb96a90d8'}
+        )
+
+    def test_restart_trigger_absent(self):
+        self.relation_ids.return_value = ['rid1']
+        self.related_units.return_value = ['nova-compute/0']
+        self.relation_get.return_value = None
+        self.assertEquals(context.RemoteRestartContext()(), {})