Fix switch connection destination when a rabbitmq cluster node disappear

In a clustered rabbitmq when a node disappears, we get a
ConnectionRefusedError because the socket get disconnected.

The socket access yields a OSError because the heartbeat
tries to reach an unreachable host (No route to host).

Catch these exceptions to ensure that we call ensure_connection for switching
the connection destination.

POC is available at github.com:4383/rabbitmq-oslo_messging-error-poc

Example:
    $ git clone git@github.com:4383/rabbitmq-oslo_messging-error-poc
    $ cd rabbitmq-oslo_messging-error-poc
    $ python -m virtualenv .
    $ source bin/activate
    $ pip install -r requirements.txt
    $ sudo podman run -d --hostname my-rabbit --name rabbit rabbitmq:3
    $ python poc.py $(sudo podman inspect rabbit | niet '.[0].NetworkSettings.IPAddress')

And in parallele in an another shell|tmux
    $ podman stop rabbit
    $ # observe the output of the poc.py script we now call ensure_connection

Now you can observe some output relative to the connection who is
modified and not catched before these changes.

Related to: https://bugzilla.redhat.com/show_bug.cgi?id=1665399

Closes-Bug: #1828841

Change-Id: I9dc1644cac0e39eb11bf05f57bde77dcf6d42ed3

oslo_messaging/_drivers/impl_rabbit.py

@@ -918,6 +918,14 @@ class Connection(object):
     def _heartbeat_thread_job(self):
         """Thread that maintains inactive connections
         """
+        # NOTE(hberaud): Python2 doesn't have ConnectionRefusedError
+        # defined so to switch connections destination on failure
+        # with python2 and python3 we need to wrapp adapt connection refused
+        try:
+            ConnectRefuseError = ConnectionRefusedError
+        except NameError:
+            ConnectRefuseError = socket.error
+
         while not self._heartbeat_exit_event.is_set():
             with self._connection_lock.for_heartbeat():
 
@@ -934,7 +942,17 @@ class Connection(object):
                             self.connection.drain_events(timeout=0.001)
                         except socket.timeout:
                             pass
+                    # NOTE(hberaud): In a clustered rabbitmq when
+                    # a node disappears, we get a ConnectionRefusedError
+                    # because the socket get disconnected.
+                    # The socket access yields a OSError because the heartbeat
+                    # tries to reach an unreachable host (No route to host).
+                    # Catch these exceptions to ensure that we call
+                    # ensure_connection for switching the
+                    # connection destination.
                     except (socket.timeout,
+                            ConnectRefuseError,
+                            OSError,
                             kombu.exceptions.OperationalError) as exc:
                         LOG.info(_LI("A recoverable connection/channel error "
                                      "occurred, trying to reconnect: %s"), exc)