Catch socket.gaierror in graphite driver

If you specify a name that can't be looked up in DNS, socket.connect()
throws socket.gaierror. We should catch and log that situation properly.

homeassistant/components/graphite.py

@@ -98,6 +98,8 @@ class GraphiteFeeder(threading.Thread):
         _LOGGER.debug('Sending to graphite: %s', lines)
         try:
             self._send_to_graphite('\n'.join(lines))
+        except socket.gaierror:
+            _LOGGER.error('Unable to connect to host %s', self._host)
         except socket.error:
             _LOGGER.exception('Failed to send data to graphite')
 

tests/components/test_graphite.py

@@ -132,6 +132,16 @@ class TestGraphite(unittest.TestCase):
             actual = mock_send.call_args_list[0][0][0].split('\n')
             self.assertEqual(sorted(expected), sorted(actual))
 
+    @mock.patch('time.time')
+    def test_send_to_graphite_errors(self, mock_time):
+        mock_time.return_value = 12345
+        state = ha.State('domain.entity', STATE_ON, {'foo': 1.0})
+        with mock.patch.object(self.gf, '_send_to_graphite') as mock_send:
+            mock_send.side_effect = socket.error
+            self.gf._report_attributes('entity', state)
+            mock_send.side_effect = socket.gaierror
+            self.gf._report_attributes('entity', state)
+
     @mock.patch('socket.socket')
     def test_send_to_graphite(self, mock_socket):
         self.gf._send_to_graphite('foo')