[wsrelay] Handle heartbeet shutdown and redis drop (#13991)

This fixes two different exceptions in wsrelay.

* One resulted from heartbeet getting ability in #13858 to gracefully
  shut down. When we saw the message come through, we didn't fully
  clean up the connection to the web node.

* The second resulted when Redis disappeared. We still want to exit in
  that case, but it's better to log a message and exit gracefully
  instead of crashing out.

Signed-off-by: Rick Elrod <rick@elrod.me>

awx/main/wsrelay.py

@@ -5,6 +5,7 @@ from typing import Dict
 
 import aiohttp
 from aiohttp import client_exceptions
+import aioredis
 
 from channels.layers import get_channel_layer
 
@@ -180,6 +181,9 @@ class WebsocketRelayConnection:
                         return
 
                     continue
+                except aioredis.errors.ConnectionClosedError:
+                    logger.info(f"Producer {name} lost connection to Redis, shutting down.")
+                    return
 
                 await websocket.send_json(wrap_broadcast_msg(group, msg))
         except ConnectionResetError:
@@ -230,28 +234,51 @@ class WebSocketRelayManager(object):
                 if ip is None:
                     # If we don't get an IP, just try the hostname, maybe it resolves
                     ip = hostname
-                if hostname is None or ip is None:
-                    logger.warning(f"Received invalid online heartbeet, missing hostname or ip: {payload}")
+                if ip is None:
+                    logger.warning(f"Received invalid online heartbeet, missing hostname and ip: {payload}")
                     return
                 self.known_hosts[hostname] = ip
                 logger.debug(f"Web host {hostname} ({ip}) online heartbeat received.")
             elif payload.get("action") == "offline":
                 hostname = payload.get("hostname")
-                if hostname is None:
-                    logger.warning(f"Received invalid offline heartbeet, missing hostname: {payload}")
+                ip = payload.get("ip")
+                if ip is None:
+                    # If we don't get an IP, just try the hostname, maybe it resolves
+                    ip = hostname
+                if ip is None:
+                    logger.warning(f"Received invalid offline heartbeet, missing hostname and ip: {payload}")
                     return
-                del self.known_hosts[hostname]
+                self.cleanup_offline_host(ip)
                 logger.debug(f"Web host {hostname} ({ip}) offline heartbeat received.")
         except Exception as e:
             # This catch-all is the same as the one above. asyncio will eat the exception
             # but we want to know about it.
             logger.exception(f"on_heartbeet exception: {e}")
 
+    def cleanup_offline_host(self, hostname):
+        """
+        Given a hostname, try to cancel its task/connection and remove it from
+        the list of hosts we know about.
+        If the host isn't in the list, assume that it was already deleted and
+        don't error.
+        """
+        if hostname in self.relay_connections:
+            self.relay_connections[hostname].cancel()
+            del self.relay_connections[hostname]
+
+        if hostname in self.known_hosts:
+            del self.known_hosts[hostname]
+
+        try:
+            self.stats_mgr.delete_remote_host_stats(hostname)
+        except KeyError:
+            pass
+
     async def run(self):
         event_loop = asyncio.get_running_loop()
 
-        stats_mgr = RelayWebsocketStatsManager(event_loop, self.local_hostname)
-        stats_mgr.start()
+        self.stats_mgr = RelayWebsocketStatsManager(event_loop, self.local_hostname)
+        self.stats_mgr.start()
 
         # Set up a pg_notify consumer for allowing web nodes to "provision" and "deprovision" themselves gracefully.
         database_conf = settings.DATABASES['default']
@@ -268,7 +295,6 @@ class WebSocketRelayManager(object):
 
         # Establishes a websocket connection to /websocket/relay on all API servers
         while True:
-            # logger.info("Current known hosts: {}".format(self.known_hosts))
             future_remote_hosts = self.known_hosts.keys()
             current_remote_hosts = self.relay_connections.keys()
             deleted_remote_hosts = set(current_remote_hosts) - set(future_remote_hosts)
@@ -297,13 +323,10 @@ class WebSocketRelayManager(object):
                 logger.info(f"Adding {new_remote_hosts} to websocket broadcast list")
 
             for h in deleted_remote_hosts:
-                self.relay_connections[h].cancel()
-                del self.relay_connections[h]
-                del self.known_hosts[h]
-                stats_mgr.delete_remote_host_stats(h)
+                self.cleanup_offline_host(h)
 
             for h in new_remote_hosts:
-                stats = stats_mgr.new_remote_host_stats(h)
+                stats = self.stats_mgr.new_remote_host_stats(h)
                 relay_connection = WebsocketRelayConnection(name=self.local_hostname, stats=stats, remote_host=self.known_hosts[h])
                 relay_connection.start()
                 self.relay_connections[h] = relay_connection