out_http: add gzip option

lib/fluent/plugin/out_http.rb

@@ -55,6 +55,8 @@ class RetryableResponse < StandardError; end
     config_param :headers, :hash, default: nil
     desc 'Additional placeholder based headers for HTTP request'
     config_param :headers_from_placeholders, :hash, default: nil
+    desc 'Compress HTTP request body'
+    config_param :compress, :enum, list: [:text, :gzip], default: :text
 
     desc 'The connection open timeout in seconds'
     config_param :open_timeout, :integer, default: nil
@@ -290,6 +292,9 @@ def set_headers(req, uri, chunk)
           req[k] = extract_placeholders(v, chunk)
         end
       end
+      if @compress == :gzip
+        req['Content-Encoding'] = "gzip"
+      end
       req['Content-Type'] = @content_type
     end
 
@@ -323,8 +328,15 @@ def create_request(chunk, uri)
               Net::HTTP::Put.new(uri.request_uri)
             end
       set_headers(req, uri, chunk)
+
       req.body = @json_array ? "[#{chunk.read.chop}]" : chunk.read
 
+      if @compress == :gzip
+        gz = Zlib::GzipWriter.new(StringIO.new)
+        gz << req.body
+        req.body = gz.close.string
+      end
+
       # At least one authentication method requires the body and other headers, so the order of this call matters
       set_auth(req, uri)
       req

test/plugin/test_out_http.rb

@@ -75,21 +75,30 @@ def run_http_server
         @@result.headers[key] = value
       end
 
+      body = ""
       data = []
+
+      case req['content-encoding']
+      when 'gzip'
+        body = Zlib::GzipReader.new(StringIO.new(req.body)).read
+      else 
+        body = req.body
+      end
+
       case req.content_type
       when 'application/x-ndjson'
-        req.body.each_line { |l|
+        body.each_line { |l|
           data << JSON.parse(l)
         }
       when 'application/json'
-        data = JSON.parse(req.body)
+        data = JSON.parse(body)
       when 'text/plain'
         # Use single_value in this test
-        req.body.each_line { |line|
+        body.each_line { |line|
           data << line.chomp
         }
       else
-        data << req.body
+        data << body
       end
       @@result.data = data
 
@@ -519,6 +528,41 @@ def test_write_with_https
     end
   end
 
+  sub_test_case 'GZIP' do
+    def server_port
+      19882
+    end
+
+    data(:json_array, [false, true])
+    data(:buffer_compress, ["text", "gzip"])
+    def test_write_with_gzip
+      d = create_driver(%[
+        endpoint http://127.0.0.1:#{server_port}/test
+        compress gzip
+        json_array #{data[:json_array]}
+        <buffer>
+          @type memory
+          compress #{data[:buffer_compress]}
+        </buffer>
+      ])
+      d.run(default_tag: 'test.http') do
+        test_events.each { |event|
+          d.feed(event)
+        }
+      end
+
+      result = @@result
+      assert_equal 'POST', result.method
+      assert_equal(
+        data[:json_array] ? 'application/json' : 'application/x-ndjson',
+        result.content_type
+      )
+      assert_equal 'gzip', result.headers['content-encoding']
+      assert_equal test_events,  result.data
+      assert_not_empty result.headers
+    end
+  end
+
   sub_test_case 'connection_reuse' do
     def server_port
       19883