I'm using Logstash 1.4.1 with Elasticsearch (installed as EC2 cluster) 1.1.1 and Elasticsearch AWS plugin 2.1.1.

To try if the Logstash is properly talking to Elasticsearch, I use -

```
bin/logstash -e 'input { stdin { } } output { elasticsearch { host => <ES_cluster_IP> } }'

```

and I get -

```
log4j, [2014-06-10T18:30:17.622]  WARN: org.elasticsearch.discovery: [logstash-ip-xxxxxxxx-20308-2010] waited for 30s and no initial state was set by the discovery
Exception in thread ">output" org.elasticsearch.discovery.MasterNotDiscoveredException: waited for [30s]
    at org.elasticsearch.action.support.master.TransportMasterNodeOperationAction$3.onTimeout(org/elasticsearch/action/support/master/TransportMasterNodeOperationAction.java:180)
    at org.elasticsearch.cluster.service.InternalClusterService$NotifyTimeout.run(org/elasticsearch/cluster/service/InternalClusterService.java:492)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(java/util/concurrent/ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(java/util/concurrent/ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(java/lang/Thread.java:744)

```

But when I use -

```
bin/logstash -e 'input { stdin { } } output { elasticsearch_http { host => <ES_cluster_IP> } }'

```

it works fine with the below warning -

```
Using milestone 2 output plugin 'elasticsearch_http'. This plugin should be stable, but if you see strange behavior, please let us know! For more information on plugin milestones, see http://logstash.net/docs/1.4.1/plugin-milestones {:level=>:warn}

```

I don't understand why can't I use `elasticsearch` instead of `elasticsearch_http` even when versions are compatible.