ProcessLauncher: reload config file in parent process on SIGHUP

Currently, when a parent process receives SIGHUP it just sends
SIGHUP to its children. While children reload their config files
and call reset on their services, parent continues to run with
old config.

Add reloading of config file and calling reset for service
on receiving SIGHUP.

Closes-Bug: #1433142
Change-Id: I132865fc5c3a12baf02f2991fc82701adfc7ed67

openstack/common/service.py

@@ -391,8 +391,14 @@ class ProcessLauncher(object):
                 if not _is_sighup_and_daemon(self.sigcaught):
                     break
 
+                cfg.CONF.reload_config_files()
+                for service in set(
+                        [wrap.service for wrap in self.children.values()]):
+                    service.reset()
+
                 for pid in self.children:
                     os.kill(pid, signal.SIGHUP)
+
                 self.running = True
                 self.sigcaught = None
         except eventlet.greenlet.GreenletExit:

tests/unit/test_service.py

@@ -412,6 +412,37 @@ class ProcessLauncherTest(test_base.BaseTestCase):
         for m in service.ProcessLauncher._signal_handlers_set:
             m.assert_called_once_with()
 
+    @mock.patch("os.kill")
+    @mock.patch("openstack.common.service.ProcessLauncher.stop")
+    @mock.patch("openstack.common.service.ProcessLauncher._respawn_children")
+    @mock.patch("openstack.common.service.ProcessLauncher.handle_signal")
+    @mock.patch("oslo_config.cfg.CONF.log_opt_values")
+    @mock.patch("openstack.common.systemd.notify_once")
+    @mock.patch("oslo_config.cfg.CONF.reload_config_files")
+    @mock.patch("openstack.common.service._is_sighup_and_daemon")
+    def test_parent_process_reload_config(self,
+                                          is_sighup_and_daemon_mock,
+                                          reload_config_files_mock,
+                                          notify_once_mock,
+                                          log_opt_values_mock,
+                                          handle_signal_mock,
+                                          respawn_children_mock,
+                                          stop_mock,
+                                          kill_mock):
+        is_sighup_and_daemon_mock.return_value = True
+        respawn_children_mock.side_effect = [None,
+                                             eventlet.greenlet.GreenletExit()]
+        launcher = service.ProcessLauncher()
+        launcher.sigcaught = 1
+        launcher.children = {}
+
+        wrap_mock = mock.Mock()
+        launcher.children[222] = wrap_mock
+        launcher.wait()
+
+        reload_config_files_mock.assert_called_once_with()
+        wrap_mock.service.reset.assert_called_once_with()
+
 
 class GracefulShutdownTestService(service.Service):
     def __init__(self):