http_response: override req.Host header properly

closes #1198

CHANGELOG.md

@@ -11,6 +11,7 @@
 - [#1195](https://github.com/influxdata/telegraf/pull/1195): Docker panic on timeout. Thanks @zstyblik!
 - [#1211](https://github.com/influxdata/telegraf/pull/1211): mongodb input. Fix possible panic. Thanks @kols!
 - [#1228](https://github.com/influxdata/telegraf/pull/1228): Fix service plugin host tag overwrite.
+- [#1198](https://github.com/influxdata/telegraf/pull/1198): http_response: override request Host header properly
 
 ## v0.13 [2016-05-11]
 

plugins/inputs/http_response/http_response.go

@@ -68,16 +68,6 @@ func CreateHttpClient(followRedirects bool, ResponseTimeout time.Duration) *http
 	return client
 }
 
-// CreateHeaders takes a map of header strings and puts them
-// into a http.Header Object
-func CreateHeaders(headers map[string]string) http.Header {
-	httpHeaders := make(http.Header)
-	for key := range headers {
-		httpHeaders.Add(key, headers[key])
-	}
-	return httpHeaders
-}
-
 // HTTPGather gathers all fields and returns any errors it encounters
 func (h *HTTPResponse) HTTPGather() (map[string]interface{}, error) {
 	// Prepare fields
@@ -93,7 +83,13 @@ func (h *HTTPResponse) HTTPGather() (map[string]interface{}, error) {
 	if err != nil {
 		return nil, err
 	}
-	request.Header = CreateHeaders(h.Headers)
+
+	for key, val := range h.Headers {
+		request.Header.Add(key, val)
+		if key == "Host" {
+			request.Host = val
+		}
+	}
 
 	// Start Timer
 	start := time.Now()

plugins/inputs/http_response/http_response_test.go

@@ -11,20 +11,6 @@ import (
 	"time"
 )
 
-func TestCreateHeaders(t *testing.T) {
-	fakeHeaders := map[string]string{
-		"Accept":        "text/plain",
-		"Content-Type":  "application/json",
-		"Cache-Control": "no-cache",
-	}
-	headers := CreateHeaders(fakeHeaders)
-	testHeaders := make(http.Header)
-	testHeaders.Add("Accept", "text/plain")
-	testHeaders.Add("Content-Type", "application/json")
-	testHeaders.Add("Cache-Control", "no-cache")
-	assert.Equal(t, testHeaders, headers)
-}
-
 func setUpTestMux() http.Handler {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/redirect", func(w http.ResponseWriter, req *http.Request) {
@@ -63,6 +49,33 @@ func setUpTestMux() http.Handler {
 	return mux
 }
 
+func TestHeaders(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		cHeader := r.Header.Get("Content-Type")
+		assert.Equal(t, "Hello", r.Host)
+		assert.Equal(t, "application/json", cHeader)
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer ts.Close()
+
+	h := &HTTPResponse{
+		Address:         ts.URL,
+		Method:          "GET",
+		ResponseTimeout: 2,
+		Headers: map[string]string{
+			"Content-Type": "application/json",
+			"Host":         "Hello",
+		},
+	}
+	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.NotNil(t, fields["response_time"])
+}
+
 func TestFields(t *testing.T) {
 	mux := setUpTestMux()
 	ts := httptest.NewServer(mux)
@@ -85,7 +98,6 @@ func TestFields(t *testing.T) {
 		assert.Equal(t, http.StatusOK, fields["http_response_code"])
 	}
 	assert.NotNil(t, fields["response_time"])
-
 }
 
 func TestRedirects(t *testing.T) {