here is the entire trace;
Sending Logstash's logs to data/GA5.2/logstash-5.2.0/logs which is now configured via log4j2.properties
[2017-02-15T13:44:06,720][INFO ][logstash.outputs.elasticsearch] Elasticsearch pool URLs updated {:changes=>{:removed=>[], :added=>[http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s]}}
[2017-02-15T13:44:06,725][INFO ][logstash.outputs.elasticsearch] Running health check to see if an Elasticsearch connection is working {:healthcheck_url=>http://logstash_system:xxxxxx@localhost:9200, :path=>"/"}
log4j:WARN No appenders could be found for logger (org.apache.http.client.protocol.RequestAuthCache).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
[2017-02-15T13:44:06,863][WARN ][logstash.outputs.elasticsearch] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>#<URI::HTTP:0x16168399 URL:http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s>, :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError, :error=>"Elasticsearch Unreachable: [http://logstash_system:xxxxxx@localhost:9200][Manticore::SocketException] Connection refused"}
[2017-02-15T13:44:06,864][INFO ][logstash.outputs.elasticsearch] New Elasticsearch output {:class=>"LogStash::Outputs::ElasticSearch", :hosts=>[#<URI::HTTP:0x4e703f0d URL:http://localhost:9200>]}
[2017-02-15T13:44:06,865][INFO ][logstash.pipeline ] Starting pipeline {"id"=>".monitoring-logstash", "pipeline.workers"=>1, "pipeline.batch.size"=>2, "pipeline.batch.delay"=>5, "pipeline.max_inflight"=>2}
[2017-02-15T13:44:06,875][INFO ][logstash.pipeline ] Pipeline .monitoring-logstash started
[2017-02-15T13:44:07,008][INFO ][logstash.pipeline ] Starting pipeline {"id"=>"main", "pipeline.workers"=>4, "pipeline.batch.size"=>125, "pipeline.batch.delay"=>5, "pipeline.max_inflight"=>500}
[2017-02-15T13:44:07,036][INFO ][logstash.pipeline ] Pipeline main started
[2017-02-15T13:44:07,124][INFO ][logstash.agent ] Successfully started Logstash API endpoint {:port=>9600}
[2017-02-15T13:44:11,878][INFO ][logstash.outputs.elasticsearch] Running health check to see if an Elasticsearch connection is working {:healthcheck_url=>http://logstash_system:xxxxxx@localhost:9200, :path=>"/"}
[2017-02-15T13:44:11,889][WARN ][logstash.outputs.elasticsearch] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>#<URI::HTTP:0x721fec92 URL:http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s>, :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError, :error=>"Elasticsearch Unreachable: [http://logstash_system:xxxxxx@localhost:9200][Manticore::SocketException] Connection refused"}
[2017-02-15T13:44:16,545][WARN ][logstash.outputs.elasticsearch] Marking url as dead. Last error: [LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError] Elasticsearch Unreachable: [http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s][Manticore::SocketException] Connection refused {:url=>http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s, :error_message=>"Elasticsearch Unreachable: [http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s][Manticore::SocketException] Connection refused", :error_class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError"}
[2017-02-15T13:44:16,546][ERROR][logstash.outputs.elasticsearch] Attempted to send a bulk request to elasticsearch' but Elasticsearch appears to be unreachable or down! {:error_message=>"Elasticsearch Unreachable: [http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s][Manticore::SocketException] Connection refused", :class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError", :will_retry_in_seconds=>2}
[2017-02-15T13:44:16,891][INFO ][logstash.outputs.elasticsearch] Running health check to see if an Elasticsearch connection is working {:healthcheck_url=>http://logstash_system:xxxxxx@localhost:9200, :path=>"/"}
[2017-02-15T13:44:16,896][WARN ][logstash.outputs.elasticsearch] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>#<URI::HTTP:0x604dcabe URL:http://logstash_system:xxxxxx@localhost:9200/_xpack/monitoring/?system_id=logstash&system_api_version=2&interval=1s>, :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError, :error=>"Elasticsearch Unreachable: [http://logstash_system:xxxxxx@localhost:9200][Manticore::SocketException] Connection refused"}
[2017-02-15T13:44:18,550][WARN ][logstash.outputs.elasticsearch] UNEXPECTED POOL ERROR {:e=>#<LogStash::Outputs::ElasticSearch::HttpClient::Pool::NoConnectionAvailableError: No Available connections>}