Add response time to httpjson plugin

closes influxdata#475

Author: titilambert

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Features
 - [#509](https://github.com/influxdb/telegraf/pull/509): Flatten JSON arrays with indices. Thanks @psilva261!
 - [#512](https://github.com/influxdata/telegraf/pull/512): Python 3 build script, add lsof dep to package. Thanks @Ormod!
+- [#475](https://github.com/influxdata/telegraf/pull/475): Add response time to httpjson plugin. Thanks @titilambert!
 
 ### Bugfixes
 - [#506](https://github.com/influxdb/telegraf/pull/506): Ping input doesn't return response time metric when timeout. Thanks @titilambert!

plugins/inputs/httpjson/httpjson.go

@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/influxdb/telegraf/internal"
 	"github.com/influxdb/telegraf/plugins/inputs"
@@ -119,7 +120,8 @@ func (h *HttpJson) gatherServer(
 	acc inputs.Accumulator,
 	serverURL string,
 ) error {
-	resp, err := h.sendRequest(serverURL)
+	resp, responseTime, err := h.sendRequest(serverURL)
+
 	if err != nil {
 		return err
 	}
@@ -141,6 +143,9 @@ func (h *HttpJson) gatherServer(
 		delete(jsonOut, tag)
 	}
 
+	if responseTime >= 0 {
+		jsonOut["response_time"] = responseTime
+	}
 	f := internal.JSONFlattener{}
 	err = f.FlattenJSON("", jsonOut)
 	if err != nil {
@@ -164,11 +169,11 @@ func (h *HttpJson) gatherServer(
 // Returns:
 //     string: body of the response
 //     error : Any error that may have occurred
-func (h *HttpJson) sendRequest(serverURL string) (string, error) {
+func (h *HttpJson) sendRequest(serverURL string) (string, float64, error) {
 	// Prepare URL
 	requestURL, err := url.Parse(serverURL)
 	if err != nil {
-		return "", fmt.Errorf("Invalid server URL \"%s\"", serverURL)
+		return "", -1, fmt.Errorf("Invalid server URL \"%s\"", serverURL)
 	}
 
 	params := url.Values{}
@@ -180,19 +185,21 @@ func (h *HttpJson) sendRequest(serverURL string) (string, error) {
 	// Create + send request
 	req, err := http.NewRequest(h.Method, requestURL.String(), nil)
 	if err != nil {
-		return "", err
+		return "", -1, err
 	}
 
+	start := time.Now()
 	resp, err := h.client.MakeRequest(req)
 	if err != nil {
-		return "", err
+		return "", -1, err
 	}
-	defer resp.Body.Close()
 
 	defer resp.Body.Close()
+	responseTime := time.Since(start).Seconds()
+
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return string(body), err
+		return string(body), responseTime, err
 	}
 
 	// Process response
@@ -203,10 +210,10 @@ func (h *HttpJson) sendRequest(serverURL string) (string, error) {
 			http.StatusText(resp.StatusCode),
 			http.StatusOK,
 			http.StatusText(http.StatusOK))
-		return string(body), err
+		return string(body), responseTime, err
 	}
 
-	return string(body), err
+	return string(body), responseTime, err
 }
 
 func init() {

plugins/inputs/httpjson/httpjson_test.go

@@ -14,7 +14,7 @@ import (
 const validJSON = `
 	{
 		"parent": {
-			"child": 3,
+			"child": 3.0,
 			"ignored_child": "hi"
 		},
 		"ignored_null": null,
@@ -126,10 +126,16 @@ func TestHttpJson200(t *testing.T) {
 		var acc testutil.Accumulator
 		err := service.Gather(&acc)
 		require.NoError(t, err)
-		assert.Equal(t, 10, acc.NFields())
+		assert.Equal(t, 12, acc.NFields())
+		// Set responsetime
+		for _, p := range acc.Points {
+			p.Fields["response_time"] = 1.0
+		}
+
 		for _, srv := range service.Servers {
 			tags := map[string]string{"server": srv}
 			mname := "httpjson_" + service.Name
+			expectedFields["response_time"] = 1.0
 			acc.AssertContainsTaggedFields(t, mname, expectedFields, tags)
 		}
 	}
@@ -188,11 +194,15 @@ func TestHttpJson200Tags(t *testing.T) {
 		if service.Name == "other_webapp" {
 			var acc testutil.Accumulator
 			err := service.Gather(&acc)
+			// Set responsetime
+			for _, p := range acc.Points {
+				p.Fields["response_time"] = 1.0
+			}
 			require.NoError(t, err)
-			assert.Equal(t, 2, acc.NFields())
+			assert.Equal(t, 4, acc.NFields())
 			for _, srv := range service.Servers {
 				tags := map[string]string{"server": srv, "role": "master", "build": "123"}
-				fields := map[string]interface{}{"value": float64(15)}
+				fields := map[string]interface{}{"value": float64(15), "response_time": float64(1)}
 				mname := "httpjson_" + service.Name
 				acc.AssertContainsTaggedFields(t, mname, fields, tags)
 			}