In the example above we use the ``setup_test()`` method to disable the
authentication handler for the ``Ping2`` controller.
+
+How to listen for manager notifications in a controller?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The manager notifies the modules of several types of cluster events, such
+as cluster logging event, etc...
+
+Each module has a "global" handler function called ``notify`` that the manager
+calls to notify the module. But this handler function must not block or spend
+too much time processing the event notification.
+For this reason we provide a notification queue that controllers can register
+themselves with to receive cluster notifications.
+
+The example below represents a controller that implements a very simple live
+log viewer page::
+
+ from __future__ import absolute_import
+
+ import collections
+
+ import cherrypy
+
+ from ..tools import ApiController, BaseController, NotificationQueue
+
+
+ @ApiController('livelog')
+ class LiveLog(BaseController):
+ log_buffer = collections.deque(maxlen=1000)
+
+ def __init__(self):
+ super(LiveLog, self).__init__()
+ NotificationQueue.register(self.log, 'clog')
+
+ def log(self, log_struct):
+ self.log_buffer.appendleft(log_struct)
+
+ @cherrypy.expose
+ def default(self):
+ ret = '<html><meta http-equiv="refresh" content="2" /><body>'
+ for l in self.log_buffer:
+ ret += "{}<br>".format(l)
+ ret += "</body></html>"
+ return ret
+
+As you can see above, the ``NotificationQueue`` class provides a register
+method that receives the function as its first argument, and receives the
+"notification type" as the second argument.
+You can omit the second argument of the ``register`` method, and in that case
+you are registering to listen all notifications of any type.
+
+Here is an list of notification types (these might change in the future) that
+can be used:
+
+* ``clog``: cluster log notifications
+* ``command``: notification when a command issued by ``MgrModule.send_command``
+ completes
+* ``perf_schema_update``: perf counters schema update
+* ``mon_map``: monitor map update
+* ``fs_map``: cephfs map update
+* ``osd_map``: OSD map update
+* ``service_map``: services (RGW, RBD-Mirror, etc.) map update
+* ``mon_status``: monitor status regular update
+* ``health``: health status regular update
+* ``pg_summary``: regular update of PG status information
+
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