Merge pull request #7 from luisfdez/master

Fix probing after "systemctl daemon-reexec"

collectd_systemd.py

@@ -16,6 +16,7 @@ def log_verbose(self, msg):
         collectd.info('{} plugin [verbose]: {}'.format(self.plugin_name, msg))
 
     def init_dbus(self):
+        self.units = {}
         self.bus = dbus.SystemBus()
         self.manager = dbus.Interface(self.bus.get_object('org.freedesktop.systemd1',
                                                           '/org/freedesktop/systemd1'),
@@ -39,7 +40,11 @@ def get_service_state(self, name):
         if not unit:
             return 'broken'
         else:
-            return unit.Get('org.freedesktop.systemd1.Unit', 'SubState')
+            try:
+                return unit.Get('org.freedesktop.systemd1.Unit', 'SubState')
+            except dbus.exceptions.DBusException as e:
+                self.log_verbose('{} plugin: failed to monitor unit {}: {}'.format(self.plugin_name, name, e))
+                return 'broken'
 
     def configure_callback(self, conf):
         for node in conf.children:
@@ -65,7 +70,13 @@ def read_callback(self):
         self.log_verbose('Read callback called')
         for name in self.services:
             full_name = name + '.service'
+
             state = self.get_service_state(full_name)
+            if state == 'broken':
+                self.log_verbose ('Unit {0} reported as broken. Reinitializing the connection to dbus & retrying.'.format(full_name))
+                self.init_dbus()
+                state = self.get_service_state(full_name)
+
             value = (1.0 if state == 'running' or state == 'reload' else 0.0)
             self.log_verbose('Sending value: {}.{}={} (state={})'
                              .format(self.plugin_name, name, value, state))

tests/test_collectd_systemd.py

@@ -77,6 +77,10 @@ def test_get_service_state(configured_mon):
     with mock.patch('dbus.Interface', side_effect=dbus.exceptions.DBusException):
         state = configured_mon.get_service_state('missing')
         assert state == 'broken'
+    with mock.patch.object(configured_mon, 'get_unit') as m:
+        m().Get.side_effect=dbus.exceptions.DBusException
+        state = configured_mon.get_service_state('broken-cache')
+        assert state == 'broken'
 
 
 def test_send_metrics(configured_mon):
@@ -94,3 +98,24 @@ def test_send_metrics(configured_mon):
             c3_kwargs = val_mock.call_args_list[2][1]
             assert c3_kwargs['plugin_instance'] == 'service3'
             assert c3_kwargs['values'] == [1]
+
+
+def test_retry_if_broken(configured_mon):
+    with mock.patch.object(configured_mon, 'get_service_state') as m:
+        m.side_effect = ['broken', 'running', 'failed', 'running']
+        with mock.patch.object(configured_mon, 'init_dbus') as idm:
+            with mock.patch('collectd.Values') as val_mock:
+                configured_mon.read_callback()
+                idm.assert_called_once()
+                assert m.call_count == 4
+                m.call_args_list[0][0][0] == m.call_args_list[1][0][0] == 'service1'
+                assert val_mock.call_count == 3
+                c1_kwargs = val_mock.call_args_list[0][1]
+                assert c1_kwargs['plugin_instance'] == 'service1'
+                assert c1_kwargs['values'] == [1]
+                c2_kwargs = val_mock.call_args_list[1][1]
+                assert c2_kwargs['plugin_instance'] == 'service2'
+                assert c2_kwargs['values'] == [0]
+                c3_kwargs = val_mock.call_args_list[2][1]
+                assert c3_kwargs['plugin_instance'] == 'service3'
+                assert c3_kwargs['values'] == [1]