adds sniffing option for transport protocol

Fixes elastic#27

lib/logstash/outputs/elasticsearch.rb

@@ -200,6 +200,10 @@ class LogStash::Outputs::ElasticSearch < LogStash::Outputs::Base
   # Set the truststore password
   config :truststore_password, :validate => :password
 
+  # Enable cluster sniffing (transport only)
+  # Asks host for the list of all cluster nodes and adds them to the hosts list
+  config :sniffing, :validate => :boolean, :default => false
+
   # helper function to replace placeholders
   # in index names to wildcards
   # example:
@@ -223,6 +227,7 @@ def register
       client_settings["cluster.name"] = @cluster if @cluster
       client_settings["network.host"] = @bind_host if @bind_host
       client_settings["transport.tcp.port"] = @bind_port if @bind_port
+      client_settings["client.transport.sniff"] = @sniffing
 
       if @node_name
         client_settings["node.name"] = @node_name

spec/outputs/elasticsearch_spec.rb

@@ -521,3 +521,31 @@ def settings_with_index(index)
     end
   end
 end
+
+describe "outputs/elasticsearch" do
+  require 'elasticsearch'
+
+  it "set sniffing in transport mode" do
+
+    config = %q[
+      output {
+        elasticsearch {
+          host => "node01"
+          protocol => "transport"
+          sniffing => true
+        }
+      }
+    ]
+
+
+    settings_class = org.elasticsearch.common.settings.ImmutableSettings
+    settings = settings_class.settingsBuilder
+
+    expect(settings_class).to receive(:settingsBuilder).and_return(settings)
+
+    pipeline = LogStash::Pipeline.new(config)
+    pipeline.run
+
+    expect(settings.build.getAsMap["client.transport.sniff"]).to eq("true")
+  end
+end