dashboard: Fix dashboard shutdown/restart

The dashboard serve method uses block which it should not as it can
cause several problems when shutting down (restarting) ceph-mgr. As a
result the restart of the ceph-mgr module will block until time-out if
the dashboard module is enabled. This fixes the problem by using a
simple simple shutdown_event instead of block() and stopping the server
afterwards.

Signed-off-by: Boris Ranto <branto@redhat.com>
(cherry picked from commit a7acd399d1455d23c28421d8f52cb339cb32f91b)

diff --git a/src/pybind/mgr/dashboard/module.py b/src/pybind/mgr/dashboard/module.py
index 55bf33d8029cc6ce8041a4c49f904fa68a27b015..964bb184751090127efb647422847e2fe833704c 100644 (file)
--- a/src/pybind/mgr/dashboard/module.py
+++ b/src/pybind/mgr/dashboard/module.py
@@ -247,6 +247,7 @@ class Module(MgrModule, SSLCherryPyConfig):
         mgr.init(self)
 
         self._stopping = threading.Event()
+        self.shutdown_event = threading.Event()
 
     @classmethod
     def can_run(cls):
@@ -291,22 +292,22 @@ class Module(MgrModule, SSLCherryPyConfig):
         cherrypy.engine.start()
         NotificationQueue.start_queue()
         TaskManager.init()
-        logger.info('Waiting for engine...')
-        cherrypy.engine.block()
+        logger.info('Engine started.')
+        # wait for the shutdown event
+        self.shutdown_event.wait()
+        self.shutdown_event.clear()
+        NotificationQueue.stop()
+        cherrypy.engine.stop()
         if 'COVERAGE_ENABLED' in os.environ:
             _cov.stop()
             _cov.save()
-        logger.info('Engine done')
+        logger.info('Engine stopped')
 
     def shutdown(self):
         super(Module, self).shutdown()
-
         SSLCherryPyConfig.shutdown(self)
-
-        logger.info('Stopping server...')
-        NotificationQueue.stop()
-        cherrypy.engine.exit()
-        logger.info('Stopped server')
+        logger.info('Stopping engine...')
+        self.shutdown_event.set()
 
     def handle_command(self, cmd):
         res = handle_option_command(cmd)
@@ -355,6 +356,7 @@ class StandbyModule(MgrStandbyModule, SSLCherryPyConfig):
     def __init__(self, *args, **kwargs):
         super(StandbyModule, self).__init__(*args, **kwargs)
         SSLCherryPyConfig.__init__(self)
+        self.shutdown_event = threading.Event()
 
         # We can set the global mgr instance to ourselves even though
         # we're just a standby, because it's enough for logging.
@@ -397,14 +399,16 @@ class StandbyModule(MgrStandbyModule, SSLCherryPyConfig):
         cherrypy.tree.mount(Root(), "{}/".format(self.url_prefix), {})
         self.log.info("Starting engine...")
         cherrypy.engine.start()
-        self.log.info("Waiting for engine...")
-        cherrypy.engine.wait(state=cherrypy.engine.states.STOPPED)
-        self.log.info("Engine done.")
+        self.log.info("Engine started...")
+        # Wait for shutdown event
+        self.shutdown_event.wait()
+        self.shutdown_event.clear()
+        cherrypy.engine.stop()
+        self.log.info("Engine stopped.")
 
     def shutdown(self):
         SSLCherryPyConfig.shutdown(self)
 
-        self.log.info("Stopping server...")
-        cherrypy.engine.wait(state=cherrypy.engine.states.STARTED)
-        cherrypy.engine.stop()
-        self.log.info("Stopped server")
+        self.log.info("Stopping engine...")
+        self.shutdown_event.set()
+        self.log.info("Stopped engine...")