feat(inputs.http_response): Add body form option (#14189)

plugins/inputs/http_response/README.md

@@ -54,6 +54,12 @@ to use them.
   # {'fake':'data'}
   # '''
 
+  ## Optional HTTP Request Body Form
+  ## Key value pairs to encode and set at URL form. Can be used with the POST
+  ## method + application/x-www-form-urlencoded content type to replicate the
+  ## POSTFORM method.
+  # body_form = { "key": "value" }
+
   ## Optional name of the field that will contain the body of the response.
   ## By default it is set to an empty String indicating that the body's
   ## content won't be added

plugins/inputs/http_response/http_response.go

@@ -38,6 +38,7 @@ type HTTPResponse struct {
 	URLs            []string `toml:"urls"`
 	HTTPProxy       string   `toml:"http_proxy"`
 	Body            string
+	BodyForm        map[string][]string `toml:"body_form"`
 	Method          string
 	ResponseTimeout config.Duration
 	HTTPHeaderTags  map[string]string `toml:"http_header_tags"`
@@ -193,7 +194,16 @@ func (h *HTTPResponse) httpGather(u string) (map[string]interface{}, map[string]
 	var body io.Reader
 	if h.Body != "" {
 		body = strings.NewReader(h.Body)
+	} else if len(h.BodyForm) != 0 {
+		values := url.Values{}
+		for k, vs := range h.BodyForm {
+			for _, v := range vs {
+				values.Add(k, v)
+			}
+		}
+		body = strings.NewReader(values.Encode())
 	}
+
 	request, err := http.NewRequest(h.Method, u, body)
 	if err != nil {
 		return nil, nil, err

plugins/inputs/http_response/http_response_test.go

@@ -98,6 +98,20 @@ func setUpTestMux() http.Handler {
 		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		fmt.Fprintf(w, "hit the good page!")
 	})
+	mux.HandleFunc("/form", func(w http.ResponseWriter, req *http.Request) {
+		body, err := io.ReadAll(req.Body)
+		defer req.Body.Close()
+		if err != nil {
+			http.Error(w, "couldn't read request body", http.StatusBadRequest)
+			return
+		}
+		if string(body) != "list=foobar&list=fizbuzz&test=42" {
+			fmt.Println(string(body))
+			w.WriteHeader(http.StatusBadRequest)
+		} else {
+			w.WriteHeader(http.StatusOK)
+		}
+	})
 	mux.HandleFunc("/invalidUTF8", func(w http.ResponseWriter, req *http.Request) {
 		w.Write([]byte{0xff, 0xfe, 0xfd}) //nolint:errcheck // ignore the returned error as the test will fail anyway
 	})
@@ -314,6 +328,46 @@ func TestResponseBodyField(t *testing.T) {
 	checkOutput(t, &acc, expectedFields, expectedTags, nil, nil)
 }
 
+func TestResponseBodyFormField(t *testing.T) {
+	mux := setUpTestMux()
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	h := &HTTPResponse{
+		Log:  testutil.Logger{},
+		URLs: []string{ts.URL + "/form"},
+		BodyForm: map[string][]string{
+			"test": {"42"},
+			"list": {"foobar", "fizbuzz"},
+		},
+		Method: "POST",
+		Headers: map[string]string{
+			"Content-Type": "application/x-www-form-urlencoded",
+		},
+		ResponseTimeout:   config.Duration(time.Second * 20),
+		ResponseBodyField: "my_body_field",
+	}
+
+	var acc testutil.Accumulator
+	require.NoError(t, h.Gather(&acc))
+
+	expectedFields := map[string]interface{}{
+		"http_response_code": http.StatusOK,
+		"result_type":        "success",
+		"result_code":        0,
+		"response_time":      nil,
+		"content_length":     nil,
+		"my_body_field":      "",
+	}
+	expectedTags := map[string]interface{}{
+		"server":      nil,
+		"method":      "POST",
+		"status_code": "200",
+		"result":      "success",
+	}
+	checkOutput(t, &acc, expectedFields, expectedTags, nil, nil)
+}
+
 func TestResponseBodyMaxSize(t *testing.T) {
 	mux := setUpTestMux()
 	ts := httptest.NewServer(mux)

plugins/inputs/http_response/sample.conf

@@ -29,6 +29,12 @@
   # {'fake':'data'}
   # '''
 
+  ## Optional HTTP Request Body Form
+  ## Key value pairs to encode and set at URL form. Can be used with the POST
+  ## method + application/x-www-form-urlencoded content type to replicate the
+  ## POSTFORM method.
+  # body_form = { "key": "value" }
+
   ## Optional name of the field that will contain the body of the response.
   ## By default it is set to an empty String indicating that the body's
   ## content won't be added