Support multiple Kafka servers

src/socketio/kafka_manager.py

@@ -24,7 +24,9 @@ class KafkaManager(PubSubManager):  # pragma: no cover
         server = socketio.Server(client_manager=socketio.KafkaManager(url))
 
     :param url: The connection URL for the Kafka server. For a default Kafka
-                store running on the same host, use ``kafka://``.
+                store running on the same host, use ``kafka://``. For a highly
+                available deployment of Kafka, pass a list with all the
+                connection URLs available in your cluster.
     :param channel: The channel name (topic) on which the server sends and
                     receives notifications. Must be the same in all the
                     servers.
@@ -44,10 +46,12 @@ class KafkaManager(PubSubManager):  # pragma: no cover
         super(KafkaManager, self).__init__(channel=channel,
                                            write_only=write_only)
 
-        self.kafka_url = url[8:] if url != 'kafka://' else 'localhost:9092'
-        self.producer = kafka.KafkaProducer(bootstrap_servers=self.kafka_url)
+        urls = [url] if isinstance(url, str) else url
+        self.kafka_urls = [url[8:] if url != 'kafka://' else 'localhost:9092'
+                           for url in urls]
+        self.producer = kafka.KafkaProducer(bootstrap_servers=self.kafka_urls)
         self.consumer = kafka.KafkaConsumer(self.channel,
-                                            bootstrap_servers=self.kafka_url)
+                                            bootstrap_servers=self.kafka_urls)
 
     def _publish(self, data):
         self.producer.send(self.channel, value=pickle.dumps(data))