When we push the data from logstash to elastic search we may encounter connect timed out error with following log trace.Before get this error logstash may read all the values but it will not be able to write it elastic search server.

[31mGot error to send bulk of actions: connect timed out {:level=>:error}←[0m 
[33mFailed to flush outgoing items {:outgoing_count=>66, :exception=>#<Manticor 
::Timeout: connect timed out>, :backtrace=>["F:/ES/logstash-1.5.1/vendor/bundl 
/jruby/1.9/gems/manticore-0.4.1-java/lib/manticore/response.rb:35:in `initializ 
'", "org/jruby/RubyProc.java:271:in `call'", "F:/ES/logstash-1.5.1/vendor/bund 
e/jruby/1.9/gems/manticore-0.4.1-java/lib/manticore/response.rb:61:in `call'", 
F:/ES/logstash-1.5.1/vendor/bundle/jruby/1.9/gems/manticore-0.4.1-java/lib/man 
icore/response.rb:225:in `call_once'", "F:/ES/logstash-1.5.1/vendor/bundle/jru 
y/1.9/gems/manticore-0.4.1-java/lib/manticore/response.rb:128:in `code'", "D:/E 
K/logstash-1.5.1/vendor/bundle/jruby/1.9/gems/elasticsearch-transport-1.0.12/li 
/elasticsearch/transport/transport/http/manticore.rb:71:in `perform_request'", 
org/jruby/RubyProc.java:271:in `call'", "F:/ES/logstash-1.5.1/vendor/bundle/jr 
by/1.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/transpor 
/base.rb:190:in `perform_request'", "F:/ES/logstash-1.5.1/vendor/bundle/jruby/ 
.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/transport/ht 
p/manticore.rb:54:in `perform_request'", "F:/ES/logstash-1.5.1/vendor/bundle/j 
uby/1.9/gems/elasticsearch-transport-1.0.12/lib/elasticsearch/transport/client. 
b:119:in `perform_request'", "F:/ES/logstash-1.5.1/vendor/bundle/jruby/1.9/gem 
/elasticsearch-api-1.0.12/lib/elasticsearch/api/actions/bulk.rb:80:in `bulk'", 
F:/ES/logstash-1.5.1/vendor/bundle/jruby/1.9/gems/logstash-output-elasticsearc 
-0.2.8-java/lib/logstash/outputs/elasticsearch/protocol.rb:103:in `bulk'", "D:/ 
LK/logstash-1.5.1/vendor/bundle/jruby/1.9/gems/logstash-output-elasticsearch-0. 
.8-java/lib/logstash/outputs/elasticsearch.rb:466:in `submit'", "F:/ES/logstas 
-1.5.1/vendor/bundle/jruby/1.9/gems/logstash-output-elasticsearch-0.2.8-java/li 
/logstash/outputs/elasticsearch.rb:490:in `flush'", "F:/ES/logstash-1.5.1/vend 
r/bundle/jruby/1.9/gems/stud-0.0.19/lib/stud/buffer.rb:219:in `buffer_flush'", 
org/jruby/RubyHash.java:1341:in `each'", "F:/ES/logstash-1.5.1/vendor/bundle/j 
uby/1.9/gems/stud-0.0.19/lib/stud/buffer.rb:216:in `buffer_flush'", "F:/ES/log 
tash-1.5.1/vendor/bundle/jruby/1.9/gems/stud-0.0.19/lib/stud/buffer.rb:193:in ` 
uffer_flush'", "F:/ES/logstash-1.5.1/vendor/bundle/jruby/1.9/gems/stud-0.0.19/ 
ib/stud/buffer.rb:112:in `buffer_initialize'", "org/jruby/RubyKernel.java:1511: 
n `loop'", "F:/ES/logstash-1.5.1/vendor/bundle/jruby/1.9/gems/stud-0.0.19/lib/ 
tud/buffer.rb:110:in `buffer_initialize'"], :level=>:warn}←[0m

Possible Reasons :

 1. Elastic Search instance might be down
2. Make sure that we have connectivity to the server where we push the data (using telnet or ping command)
3. It should not be blocked by the firewall. Above are the possible scenarios we may get that error.