Add custom headers (#267)

* [feat] Add support for @custom_headers

README.md

@@ -288,6 +288,10 @@ Splunk app name using this plugin (default to `hec_plugin_gem`)
 
 The version of Splunk app using this this plugin (default to plugin version)
 
+### custom_headers (Hash) (Optional)
+
+Hash of custom headers to be added to the HTTP request. Used to populate [`override_headers`](https://docs.seattlerb.org/net-http-persistent/Net/HTTP/Persistent.html#attribute-i-override_headers) attribute of the underlying `Net::HTTP::Persistent` connection.
+
 #### When `data_type` is `event`
 
 In this case, parameters inside `<fields>` are used as indexed fields and removed from the original input events. Please see the "Add a "fields" property at the top JSON level" [here](http://dev.splunk.com/view/event-collector/SP-CAAAFB6) for details. Given we have configuration like

lib/fluent/plugin/out_splunk_hec.rb

@@ -134,6 +134,9 @@ class SplunkHecOutput < SplunkOutput
     DESC
     config_param :non_utf8_replacement_string, :string, :default => ' '
 
+    desc 'Any custom headers to include alongside requests made to Splunk'
+    config_param :custom_headers, :hash, :default => {}
+
     def initialize
       super
       @default_host = Socket.gethostname
@@ -168,7 +171,9 @@ def start
         c.override_headers['Authorization'] = "Splunk #{@hec_token}"
         c.override_headers['__splunk_app_name'] = "#{@app_name}"
         c.override_headers['__splunk_app_version'] = "#{@app_version}"
-
+        @custom_headers.each do |header, value|
+          c.override_headers[header] = value
+        end
       end
     end
 

test/fluent/plugin/out_splunk_hec_test.rb

@@ -66,6 +66,13 @@
     it 'should support enabling gzip' do
       expect(create_hec_output_driver('hec_host hec_token', 'gzip_compression true').instance.gzip_compression).must_equal true
     end
+    it 'should define custom_headers as {} (hash) initially' do
+      assert_empty(create_hec_output_driver('hec_host hec_token').instance.custom_headers)
+      expect(create_hec_output_driver('hec_host hec_token').instance.custom_headers).is_a? Hash
+    end
+    it 'should allow setting custom_headers' do
+      assert_equal(create_hec_output_driver('hec_host hec_token', 'custom_headers {"custom":"header"}').instance.custom_headers, {"custom" => "header"})
+    end
   end
 
   describe 'hec_host validation' do