http_response : Add in support for looking for substring in response (#2204)

* Add in support for looking for substring in response

* Add note to CHANGELOG.md

* Switch from substring match to regex match

* Requested code changes

* Make requested changes and refactor to avoid nested if-else.

* Convert tabs to space and compile regex once

plugins/inputs/http_response/README.md

@@ -23,6 +23,11 @@ This input plugin will test HTTP/HTTPS connections.
   # {'fake':'data'}
   # '''
 
+  ## Optional substring or regex match in body of the response
+  ## response_string_match = "\"service_status\": \"up\""
+  ## response_string_match = "ok"
+  ## response_string_match = "\".*_status\".?:.?\"up\""
+
   ## Optional SSL Config
   # ssl_ca = "/etc/telegraf/ca.pem"
   # ssl_cert = "/etc/telegraf/cert.pem"

plugins/inputs/http_response/http_response.go

@@ -3,8 +3,11 @@ package http_response
 import (
 	"errors"
 	"io"
+	"io/ioutil"
+	"log"
 	"net/http"
 	"net/url"
+	"regexp"
 	"strings"
 	"time"
 
@@ -15,12 +18,14 @@ import (
 
 // HTTPResponse struct
 type HTTPResponse struct {
-	Address         string
-	Body            string
-	Method          string
-	ResponseTimeout internal.Duration
-	Headers         map[string]string
-	FollowRedirects bool
+	Address             string
+	Body                string
+	Method              string
+	ResponseTimeout     internal.Duration
+	Headers             map[string]string
+	FollowRedirects     bool
+	ResponseStringMatch string
+	compiledStringMatch *regexp.Regexp
 
 	// Path to CA file
 	SSLCA string `toml:"ssl_ca"`
@@ -54,6 +59,11 @@ var sampleConfig = `
   # {'fake':'data'}
   # '''
 
+  ## Optional substring or regex match in body of the response
+  ## response_string_match = "\"service_status\": \"up\""
+  ## response_string_match = "ok"
+  ## response_string_match = "\".*_status\".?:.?\"up\""
+
   ## Optional SSL Config
   # ssl_ca = "/etc/telegraf/ca.pem"
   # ssl_cert = "/etc/telegraf/cert.pem"
@@ -137,6 +147,35 @@ func (h *HTTPResponse) HTTPGather() (map[string]interface{}, error) {
 	}
 	fields["response_time"] = time.Since(start).Seconds()
 	fields["http_response_code"] = resp.StatusCode
+
+	// Check the response for a regex match.
+	if h.ResponseStringMatch != "" {
+
+		// Compile once and reuse
+		if h.compiledStringMatch == nil {
+			h.compiledStringMatch = regexp.MustCompile(h.ResponseStringMatch)
+			if err != nil {
+				log.Printf("E! Failed to compile regular expression %s : %s", h.ResponseStringMatch, err)
+				fields["response_string_match"] = 0
+				return fields, nil
+			}
+		}
+
+		bodyBytes, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			log.Printf("E! Failed to read body of HTTP Response : %s", err)
+			fields["response_string_match"] = 0
+			return fields, nil
+		}
+
+		if h.compiledStringMatch.Match(bodyBytes) {
+			fields["response_string_match"] = 1
+		} else {
+			fields["response_string_match"] = 0
+		}
+
+	}
+
 	return fields, nil
 }
 

plugins/inputs/http_response/http_response_test.go

@@ -22,6 +22,9 @@ func setUpTestMux() http.Handler {
 	mux.HandleFunc("/good", func(w http.ResponseWriter, req *http.Request) {
 		fmt.Fprintf(w, "hit the good page!")
 	})
+	mux.HandleFunc("/jsonresponse", func(w http.ResponseWriter, req *http.Request) {
+		fmt.Fprintf(w, "\"service_status\": \"up\", \"healthy\" : \"true\"")
+	})
 	mux.HandleFunc("/badredirect", func(w http.ResponseWriter, req *http.Request) {
 		http.Redirect(w, req, "/badredirect", http.StatusMovedPermanently)
 	})
@@ -236,6 +239,87 @@ func TestBody(t *testing.T) {
 	}
 }
 
+func TestStringMatch(t *testing.T) {
+	mux := setUpTestMux()
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	h := &HTTPResponse{
+		Address:             ts.URL + "/good",
+		Body:                "{ 'test': 'data'}",
+		Method:              "GET",
+		ResponseStringMatch: "hit the good page",
+		ResponseTimeout:     internal.Duration{Duration: time.Second * 20},
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+		},
+		FollowRedirects: true,
+	}
+	fields, err := h.HTTPGather()
+	require.NoError(t, err)
+	assert.NotEmpty(t, fields)
+	if assert.NotNil(t, fields["http_response_code"]) {
+		assert.Equal(t, http.StatusOK, fields["http_response_code"])
+	}
+	assert.Equal(t, 1, fields["response_string_match"])
+	assert.NotNil(t, fields["response_time"])
+
+}
+
+func TestStringMatchJson(t *testing.T) {
+	mux := setUpTestMux()
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	h := &HTTPResponse{
+		Address:             ts.URL + "/jsonresponse",
+		Body:                "{ 'test': 'data'}",
+		Method:              "GET",
+		ResponseStringMatch: "\"service_status\": \"up\"",
+		ResponseTimeout:     internal.Duration{Duration: time.Second * 20},
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+		},
+		FollowRedirects: true,
+	}
+	fields, err := h.HTTPGather()
+	require.NoError(t, err)
+	assert.NotEmpty(t, fields)
+	if assert.NotNil(t, fields["http_response_code"]) {
+		assert.Equal(t, http.StatusOK, fields["http_response_code"])
+	}
+	assert.Equal(t, 1, fields["response_string_match"])
+	assert.NotNil(t, fields["response_time"])
+
+}
+
+func TestStringMatchFail(t *testing.T) {
+	mux := setUpTestMux()
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	h := &HTTPResponse{
+		Address:             ts.URL + "/good",
+		Body:                "{ 'test': 'data'}",
+		Method:              "GET",
+		ResponseStringMatch: "hit the bad page",
+		ResponseTimeout:     internal.Duration{Duration: time.Second * 20},
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+		},
+		FollowRedirects: true,
+	}
+	fields, err := h.HTTPGather()
+	require.NoError(t, err)
+	assert.NotEmpty(t, fields)
+	if assert.NotNil(t, fields["http_response_code"]) {
+		assert.Equal(t, http.StatusOK, fields["http_response_code"])
+	}
+	assert.Equal(t, 0, fields["response_string_match"])
+	assert.NotNil(t, fields["response_time"])
+
+}
+
 func TestTimeout(t *testing.T) {
 	mux := setUpTestMux()
 	ts := httptest.NewServer(mux)