Add content_length metric to http_response input plugin (#6261)

plugins/inputs/http_response/README.md

@@ -61,6 +61,7 @@ This input plugin checks HTTP/HTTPS connections.
     - result ([see below](#result--result_code))
   - fields:
     - response_time (float, seconds)
+    - content_length (int, response body length)
     - response_string_match (int, 0 = mismatch / body read error, 1 = match)
     - http_response_code (int, response status code)
 	- result_type (string, deprecated in 1.6: use `result` tag and `result_code` field)
@@ -85,5 +86,5 @@ This tag is used to expose network and plugin errors. HTTP errors are considered
 ### Example Output:
 
 ```
-http_response,method=GET,server=http://www.github.com,status_code=200,result=success http_response_code=200i,response_time=6.223266528,result_type="success",result_code=0i 1459419354977857955
+http_response,method=GET,result=success,server=http://github.com,status_code=200 content_length=87878i,http_response_code=200i,response_time=0.937655534,result_code=0i,result_type="success" 1565839598000000000
 ```

plugins/inputs/http_response/http_response.go

@@ -272,26 +272,27 @@ func (h *HTTPResponse) httpGather(u string) (map[string]interface{}, map[string]
 
 	// This function closes the response body, as
 	// required by the net/http library
-	defer func() {
+	defer resp.Body.Close()
-		io.Copy(ioutil.Discard, resp.Body)
-		resp.Body.Close()
-	}()
 
 	// Set log the HTTP response code
 	tags["status_code"] = strconv.Itoa(resp.StatusCode)
 	fields["http_response_code"] = resp.StatusCode
 
-	// Check the response for a regex match.
-	if h.ResponseStringMatch != "" {
-
 	bodyBytes, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
 		log.Printf("D! Failed to read body of HTTP Response : %s", err)
 		setResult("body_read_error", fields, tags)
+		fields["content_length"] = len(bodyBytes)
+		if h.ResponseStringMatch != "" {
 			fields["response_string_match"] = 0
+		}
 		return fields, tags, nil
 	}
 
+	fields["content_length"] = len(bodyBytes)
+
+	// Check the response for a regex match.
+	if h.ResponseStringMatch != "" {
 		if h.compiledStringMatch.Match(bodyBytes) {
 			setResult("success", fields, tags)
 			fields["response_string_match"] = 1

plugins/inputs/http_response/http_response_test.go

@@ -165,6 +165,7 @@ func TestHeaders(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -201,6 +202,7 @@ func TestFields(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -262,6 +264,7 @@ func TestInterface(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -297,6 +300,7 @@ func TestRedirects(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -362,6 +366,7 @@ func TestMethod(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -391,6 +396,7 @@ func TestMethod(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags = map[string]interface{}{
 		"server":      nil,
@@ -421,6 +427,7 @@ func TestMethod(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags = map[string]interface{}{
 		"server":      nil,
@@ -456,6 +463,7 @@ func TestBody(t *testing.T) {
 		"result_type":        "success",
 		"result_code":        0,
 		"response_time":      nil,
+		"content_length":     nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -520,6 +528,7 @@ func TestStringMatch(t *testing.T) {
 		"result_type":           "success",
 		"result_code":           0,
 		"response_time":         nil,
+		"content_length":        nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -556,6 +565,7 @@ func TestStringMatchJson(t *testing.T) {
 		"result_type":           "success",
 		"result_code":           0,
 		"response_time":         nil,
+		"content_length":        nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -593,6 +603,7 @@ func TestStringMatchFail(t *testing.T) {
 		"result_type":           "response_string_mismatch",
 		"result_code":           1,
 		"response_time":         nil,
+		"content_length":        nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -635,7 +646,7 @@ func TestTimeout(t *testing.T) {
 		"method": "GET",
 		"result": "timeout",
 	}
-	absentFields := []string{"http_response_code", "response_time", "response_string_match"}
+	absentFields := []string{"http_response_code", "response_time", "content_length", "response_string_match"}
 	absentTags := []string{"status_code"}
 	checkOutput(t, &acc, expectedFields, expectedTags, absentFields, absentTags)
 }
@@ -662,7 +673,7 @@ func TestPluginErrors(t *testing.T) {
 	err := h.Gather(&acc)
 	require.Error(t, err)
 
-	absentFields := []string{"http_response_code", "response_time", "response_string_match", "result_type", "result_code"}
+	absentFields := []string{"http_response_code", "response_time", "content_length", "response_string_match", "result_type", "result_code"}
 	absentTags := []string{"status_code", "result", "server", "method"}
 	checkOutput(t, &acc, nil, nil, absentFields, absentTags)
 
@@ -686,6 +697,7 @@ func TestPluginErrors(t *testing.T) {
 		"result_type":           "body_read_error",
 		"result_code":           2,
 		"response_time":         nil,
+		"content_length":        nil,
 	}
 	expectedTags := map[string]interface{}{
 		"server":      nil,
@@ -719,7 +731,7 @@ func TestNetworkErrors(t *testing.T) {
 		"method": "GET",
 		"result": "dns_error",
 	}
-	absentFields := []string{"http_response_code", "response_time", "response_string_match"}
+	absentFields := []string{"http_response_code", "response_time", "content_length", "response_string_match"}
 	absentTags := []string{"status_code"}
 	checkOutput(t, &acc, expectedFields, expectedTags, absentFields, absentTags)
 
@@ -745,7 +757,73 @@ func TestNetworkErrors(t *testing.T) {
 		"method": "GET",
 		"result": "connection_failed",
 	}
-	absentFields = []string{"http_response_code", "response_time", "response_string_match"}
+	absentFields = []string{"http_response_code", "response_time", "content_length", "response_string_match"}
 	absentTags = []string{"status_code"}
 	checkOutput(t, &acc, expectedFields, expectedTags, absentFields, absentTags)
 }
+
+func TestContentLength(t *testing.T) {
+	mux := setUpTestMux()
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	h := &HTTPResponse{
+		URLs:            []string{ts.URL + "/good"},
+		Body:            "{ 'test': 'data'}",
+		Method:          "GET",
+		ResponseTimeout: internal.Duration{Duration: time.Second * 20},
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+		},
+		FollowRedirects: true,
+	}
+	var acc testutil.Accumulator
+	err := h.Gather(&acc)
+	require.NoError(t, err)
+
+	expectedFields := map[string]interface{}{
+		"http_response_code": http.StatusOK,
+		"result_type":        "success",
+		"result_code":        0,
+		"response_time":      nil,
+		"content_length":     len([]byte("hit the good page!")),
+	}
+	expectedTags := map[string]interface{}{
+		"server":      nil,
+		"method":      "GET",
+		"status_code": "200",
+		"result":      "success",
+	}
+	absentFields := []string{"response_string_match"}
+	checkOutput(t, &acc, expectedFields, expectedTags, absentFields, nil)
+
+	h = &HTTPResponse{
+		URLs:            []string{ts.URL + "/musthaveabody"},
+		Body:            "{ 'test': 'data'}",
+		Method:          "GET",
+		ResponseTimeout: internal.Duration{Duration: time.Second * 20},
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+		},
+		FollowRedirects: true,
+	}
+	acc = testutil.Accumulator{}
+	err = h.Gather(&acc)
+	require.NoError(t, err)
+
+	expectedFields = map[string]interface{}{
+		"http_response_code": http.StatusOK,
+		"result_type":        "success",
+		"result_code":        0,
+		"response_time":      nil,
+		"content_length":     len([]byte("sent a body!")),
+	}
+	expectedTags = map[string]interface{}{
+		"server":      nil,
+		"method":      "GET",
+		"status_code": "200",
+		"result":      "success",
+	}
+	absentFields = []string{"response_string_match"}
+	checkOutput(t, &acc, expectedFields, expectedTags, absentFields, nil)
+}