slackParserFunc, parserFunc with Response

Slack messages are acknowledged with code 200, message 'ok'
code statically answered with 204 and empty message before
slackParserFunc - rudimentary slack webhook parser

handler.go

@@ -6,8 +6,17 @@ import (
 	"net/http"
 )
 
+type Response struct {
+   Message string
+   Code    int
+}
+
+func errorResponse() (Response) {
+   return Response{"", http.StatusInternalServerError}
+}
+
 // interface for parser functions (grafana, prometheus, ...)
-type parserFunc func(*http.Request) (string, error)
+type parserFunc func(*http.Request) (string, error, Response)
 
 type messageHandler struct {
 	messages   chan<- string // chan to xmpp client
@@ -17,13 +26,14 @@ type messageHandler struct {
 // http request handler
 func (h *messageHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// parse/generate message from http request
-	m, err := h.parserFunc(r)
+	m, err, response := h.parserFunc(r)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
 	}
 	// send message to xmpp client
 	h.messages <- m
-	w.WriteHeader(http.StatusNoContent)
+	w.WriteHeader(response.Code)
+   w.Write( []byte(response.Message) )
 }
 
 // returns new handler with a given parser function
@@ -37,11 +47,11 @@ func newMessageHandler(m chan<- string, f parserFunc) *messageHandler {
 /*************
 GRAFANA PARSER
 *************/
-func grafanaParserFunc(r *http.Request) (string, error) {
+func grafanaParserFunc(r *http.Request) (string, error, Response) {
 	// get alert data from request
 	body, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		return "", err
+		return "", err, errorResponse()
 	}
 
 	// grafana alert struct
@@ -55,7 +65,7 @@ func grafanaParserFunc(r *http.Request) (string, error) {
 	// parse body into the alert struct
 	err = json.Unmarshal(body, &alert)
 	if err != nil {
-		return "", err
+		return "", err, errorResponse()
 	}
 
 	// contruct alert message
@@ -67,7 +77,7 @@ func grafanaParserFunc(r *http.Request) (string, error) {
 		message = ":( " + alert.Title + "\n" + alert.Message + "\n" + alert.RuleURL
 	}
 
-	return message, nil
+	return message, nil, Response{"", http.StatusNoContent}
 }
 
 /*************
@@ -96,11 +106,11 @@ func nonemptyAppendNewline(message string) (string) {
    return message+"\n"
 }
 
-func slackParserFunc(r *http.Request) (string, error) {
+func slackParserFunc(r *http.Request) (string, error, Response) {
 	// get alert data from request
 	body, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		return "", err
+		return "", err, errorResponse()
 	}
 
 	// grafana alert struct
@@ -109,7 +119,7 @@ func slackParserFunc(r *http.Request) (string, error) {
 	// parse body into the alert struct
 	err = json.Unmarshal(body, &alert)
 	if err != nil {
-		return "", err
+		return "", err, Response{"", http.StatusInternalServerError}
 	}
 
 	// contruct alert message
@@ -121,10 +131,11 @@ func slackParserFunc(r *http.Request) (string, error) {
 
    for _, attachment := range alert.Attachments {
       message = nonemptyAppendNewline(message)
-      message = message + attachment.Title+": "+attachment.TitleLink+"\n"
-      message = message + attachment.Text
+      message += attachment.Title+"\n"
+      message += attachment.TitleLink+"\n\n"
+      message += attachment.Text
    }
 
 
-	return message, nil
+	return message, nil, Response{"ok", http.StatusOK}
 }