Added a messsage key to distribute payloads evenly among distinct partitions

Author: pablete

lib/logstash/outputs/kafka.rb

@@ -1,3 +1,4 @@
+require 'zlib'
 require 'logstash/namespace'
 require 'logstash/outputs/base'
 
@@ -136,7 +137,7 @@ def register
 
     @codec.on_event do |event|
       begin
-        @producer.send_msg(@topic_id,nil,event)
+        @producer.send_msg(@topic_id, Zlib::crc32(event).to_s, event)
       rescue LogStash::ShutdownSignal
         @logger.info('Kafka producer got shutdown signal')
       rescue => e