Attempted to send a bulk request to elasticsearch' but Elasticsearch appears to be unreachable or down!

[theo.ptz (theo)]

Hi guys.

I've got this error today:
"Attempted to send a bulk request to elasticsearch' but Elasticsearch appears to be unreachable or down!"

And i can't figure out what's wrong with my ELK cluster.

ELK cluster is green, and i can get response from ELK cluster (via curl).

Any advice would be appreciated.

Thanks

[alexhuang]

I have the same problem with you, and my version is elk 5.6.0

there are five nodes in my elasticsearch cluster, one master node without any data, and four datanodes.
all of them are 16core cpu, and 64GB memory, no ssd disk.

The error messages are like this:
[2017-11-05T14:59:08,062][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://192.168.137.168:9200/][Manticore::SocketTimeout] Read timed out", :class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError", :will_retry_in_seconds=>2}
[2017-11-05T14:59:08,801][WARN ][logstash.outputs.elasticsearch] Marking url as dead. Last error: [LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError] Elasticsearch Unreachable: [http://192.168.103.50:9200/][Manticore::SocketTimeout] Read timed out {:url=>http://192.168.103.50:9200/, :error_message=>"Elasticsearch Unreachable: [http://192.168.103.50:9200/][Manticore::SocketTimeout] Read timed out", :error_class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError"}
[2017-11-05T14:59:08,801][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://192.168.103.50:9200/][Manticore::SocketTimeout] Read timed out", :class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError", :will_retry_in_seconds=>2}

I found that, when the error occurs, the elasticsearch cluster is green, and can get response from elasticsearch cluster via curl, also the elasticsearch cluster load is not very high.

Any advice would be appreciated.

Thanks