Implement http stats.

plugins/elasticsearch/elasticsearch.go

@@ -23,6 +23,7 @@ type node struct {
 	Network    interface{}       `json:"network"`
 	FS         interface{}       `json:"fs"`
 	Transport  interface{}       `json:"transport"`
+	HTTP       interface{}       `json:"http"`
 }
 
 const sampleConfig = `
@@ -127,6 +128,9 @@ func (e *Elasticsearch) gatherUrl(url string, acc plugins.Accumulator) error {
 		if err := e.parseInterface(acc, "transport", tags, n.Transport); err != nil {
 			return err
 		}
+		if err := e.parseInterface(acc, "http", tags, n.HTTP); err != nil {
+			return err
+		}
 	}
 
 	return nil

plugins/elasticsearch/elasticsearch_test.go

@@ -82,4 +82,7 @@ func TestElasticsearch(t *testing.T) {
 	for key, val := range transportExpected {
 		assert.NoError(t, acc.ValidateTaggedValue(key, val, tags))
 	}
+	for key, val := range httpExpected {
+		assert.NoError(t, acc.ValidateTaggedValue(key, val, tags))
+	}
 }

plugins/elasticsearch/testdata_test.go

@@ -407,6 +407,10 @@ const statsResponse = `
         "rx_size_in_bytes": 1380,
         "tx_count": 6,
         "tx_size_in_bytes": 1380
+      },
+      "http": {
+        "current_open": 3,
+        "total_opened": 3
       }
     }
   }
@@ -682,3 +686,8 @@ var transportExpected = map[string]float64{
 	"transport_tx_count":         6,
 	"transport_tx_size_in_bytes": 1380,
 }
+
+var httpExpected = map[string]float64{
+	"http_current_open": 3,
+	"http_total_opened": 3,
+}