Enable oslo_config mutable configurations

This patch enables oslo_config mutable configuration for the Octavia
control plane processes. The configuration will be updated when the
parent process receives a HUP signal.
This completes the Rocky goal: Enable mutable configuration.

Change-Id: Idaf608c6e5fd2fa74a68c3b562be441a20107a50
Story: 2001545
Task: 6391

octavia/cmd/health_manager.py

@@ -13,6 +13,7 @@
 # under the License.
 #
 
+from functools import partial
 import multiprocessing
 import os
 import signal
@@ -34,8 +35,13 @@ CONF = cfg.CONF
 LOG = logging.getLogger(__name__)
 
 
+def _mutate_config(*args, **kwargs):
+    CONF.mutate_config_files()
+
+
 def hm_listener(exit_event):
     signal.signal(signal.SIGINT, signal.SIG_IGN)
+    signal.signal(signal.SIGHUP, _mutate_config)
     udp_getter = heartbeat_udp.UDPStatusGetter()
     while not exit_event.is_set():
         try:
@@ -50,6 +56,7 @@ def hm_listener(exit_event):
 
 def hm_health_check(exit_event):
     hm = health_manager.HealthManager(exit_event)
+    signal.signal(signal.SIGHUP, _mutate_config)
 
     @periodics.periodic(CONF.health_manager.health_check_interval,
                         run_immediately=True)
@@ -69,6 +76,13 @@ def hm_health_check(exit_event):
     health_check.start()
 
 
+def _handle_mutate_config(listener_proc_pid, check_proc_pid, *args, **kwargs):
+    LOG.info("Health Manager recieved HUP signal, mutating config.")
+    _mutate_config()
+    os.kill(listener_proc_pid, signal.SIGHUP)
+    os.kill(check_proc_pid, signal.SIGHUP)
+
+
 def main():
     service.prepare_service(sys.argv)
 
@@ -99,6 +113,8 @@ def main():
         hm_listener_proc.join()
 
     signal.signal(signal.SIGTERM, process_cleanup)
+    signal.signal(signal.SIGHUP, partial(
+        _handle_mutate_config, hm_listener_proc.pid, hm_health_check_proc.pid))
 
     try:
         for process in processes:

octavia/cmd/house_keeping.py

@@ -14,6 +14,7 @@
 #
 
 import datetime
+import signal
 import sys
 import threading
 import time
@@ -78,6 +79,11 @@ def cert_rotation():
         cert_rotate_thread_event.wait(interval)
 
 
+def _mutate_config(*args, **kwargs):
+    LOG.info("Housekeeping recieved HUP signal, mutating config.")
+    CONF.mutate_config_files()
+
+
 def main():
     service.prepare_service(sys.argv)
 
@@ -101,6 +107,8 @@ def main():
     cert_rotate_thread.daemon = True
     cert_rotate_thread.start()
 
+    signal.signal(signal.SIGHUP, _mutate_config)
+
     # Try-Exception block should be at the end to gracefully exit threads
     try:
         while True:

octavia/cmd/octavia_worker.py

@@ -34,5 +34,5 @@ def main():
     sm = cotyledon.ServiceManager()
     sm.add(consumer.ConsumerService, workers=CONF.controller_worker.workers,
            args=(CONF,))
-    oslo_config_glue.setup(sm, CONF)
+    oslo_config_glue.setup(sm, CONF, reload_method="mutate")
     sm.run()

octavia/tests/unit/cmd/test_health_manager.py

@@ -93,3 +93,13 @@ class TestHealthManagerCMD(base.TestCase):
         mock_health_proc.join.assert_called_once_with()
         mock_kill.assert_called_once_with(mock_health_proc.pid,
                                           signal.SIGINT)
+
+    @mock.patch('os.kill')
+    @mock.patch('oslo_config.cfg.CONF.mutate_config_files')
+    def test_handle_mutate_config(self, mock_mutate, mock_kill):
+        health_manager._handle_mutate_config(1, 2)
+
+        mock_mutate.assert_called_once()
+
+        calls = [mock.call(1, signal.SIGHUP), mock.call(2, signal.SIGHUP)]
+        mock_kill.assert_has_calls(calls)

octavia/tests/unit/cmd/test_house_keeping.py

@@ -188,3 +188,9 @@ class TestHouseKeepingCMD(base.TestCase):
         spare_amp_thread_mock.join.assert_called_once_with()
         db_cleanup_thread_mock.join.assert_called_once_with()
         cert_rotate_thread_mock.join.assert_called_once_with()
+
+    @mock.patch('oslo_config.cfg.CONF.mutate_config_files')
+    def test_mutate_config(self, mock_mutate):
+        house_keeping._mutate_config()
+
+        mock_mutate.assert_called_once()

releasenotes/notes/enable-mutable-configuration-1d7f62a133148767.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    You can now update the running configuration of the Octavia control
+    plane processes by sending the parent process a "HUP" signal.
+    Note: The configuration item must support mutation.