Do not attach empty 'node' metadata

.gitignore

@@ -0,0 +1 @@
+vendor

fluent-plugin-enhance-k8s-metadata/lib/fluent/plugin/filter_enhance_k8s_metadata.rb

@@ -86,7 +86,7 @@ def decorate_record(record)
           service = @pods_to_services[pod_name] unless @pods_to_services.nil?
           metadata['service'] = {'service' => service.sort!.join('_')} if !(service.nil? || service.empty?)
 
-          if @data_type == 'metrics' && (record['node'].nil? || record['node'] == "")
+          if @data_type == 'metrics' && (record['node'].nil? || record['node'] == "") && !metadata['node'].nil?
             record['node'] = metadata['node']
           end
 

fluent-plugin-enhance-k8s-metadata/test/plugin/test_filter_enhance_k8s_metadata.rb

@@ -56,11 +56,25 @@ class EnhanceK8sMetadataFilterTest < Test::Unit::TestCase
       driver = create_driver(conf)
 
       input_record = get_test_record[2]
-      assert_nil input_record['node']
+      assert_false input_record.key?('node')
       record = driver.filter('tag', 'time', input_record)
 
       assert_equal 'ip-172-20-62-242.us-west-1.compute.internal', record['node']
     end
+
+    test 'do not attach node metadata to metrics when not found' do
+      conf = %{
+        kubernetes_url http://localhost:8080
+        data_type metrics
+      }
+      driver = create_driver(conf)
+
+      input_record = get_test_record[3]
+      assert_false input_record.key?('node')
+      record = driver.filter('tag', 'time', input_record)
+
+      assert_false record.key?('node')
+    end
   end
 
   private

fluent-plugin-enhance-k8s-metadata/test/resources/records.json

@@ -46,6 +46,10 @@
       "@metric": "http_request_size_bytes_sum",
       "@timestamp": 1550862304339,
       "@value": 1619905.0
+    },
+    {
+      "pod": "nonexistent-pod",
+      "namespace": "non-exist"
     }
   ]
-}
+}