Support timezone

Fix #73

Signed-off-by: Kenji Okimoto <okimoto@clear-code.com>

Author: okkez

lib/fluent/plugin/grok.rb

@@ -27,6 +27,8 @@ def initialize(plugin, conf)
       @multiline_mode = false
       @conf = conf
       @plugin = plugin
+      @time_format = nil
+      @timezone = nil
       if @plugin.respond_to?(:firstline?)
         @multiline_mode = true
       end
@@ -39,6 +41,9 @@ def initialize(plugin, conf)
       if @plugin.respond_to?(:time_format)
         @time_format = @plugin.time_format
       end
+      if @plugin.respond_to?(:timezon)
+        @timezone = @plugin.timezone
+      end
     end
 
     def add_patterns_from_file(path)
@@ -105,6 +110,9 @@ def expand_pattern_expression_grok_section(conf)
       if conf["time_format"] || @time_format
         _conf["time_format"] = conf["time_format"] || @time_format
       end
+      if conf["timezone"] || @timezone
+        _conf["timezone"] = conf["timezone"] || @timezone
+      end
       _conf["expression"] = regexp
       config = Fluent::Config::Element.new("parse", "", _conf, [])
       parser = Fluent::Plugin::RegexpParser.new

lib/fluent/plugin/parser_grok.rb

@@ -25,6 +25,7 @@ class GrokParser < Parser
         config_param :keep_time_key, :bool, default: false
         config_param :time_key, :string, default: "time"
         config_param :time_format, :string, default: nil
+        config_param :timezone, :string, default: nil
       end
 
       def initialize

test/test_grok_parser.rb

@@ -374,6 +374,21 @@ class GrokParserTest < ::Test::Unit::TestCase
         assert_equal(expected_record, record)
       end
     end
+
+    test "timezone" do
+      d = create_driver(%[
+        <grok>
+          pattern %{TIMESTAMP_ISO8601:time} %{GREEDYDATA:message}
+          time_key time
+          time_format %Y-%m-%d %H:%M:%S
+          timezone Europe/Berlin
+        </grok>
+      ])
+      d.instance.parse("2019-02-01 12:34:56 This is test") do |time, record|
+        assert_equal(event_time("2019-02-01 12:34:56 +0100"), time)
+        assert_equal({ "message" => "This is test" }, record)
+      end
+    end
   end
 
   private