refactored slack parser / reorganized parser functions

handler.go

@@ -1,22 +1,11 @@
 package main
 
 import (
-	"encoding/json"
-	"io/ioutil"
 	"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, Response)
+// interface for parser functions
+type parserFunc func(*http.Request) (string, error)
 
 type messageHandler struct {
 	messages   chan<- string // chan to xmpp client
@@ -26,14 +15,16 @@ type messageHandler struct {
 // http request handler
 func (h *messageHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// parse/generate message from http request
-	m, err, response := h.parserFunc(r)
+	m, err := h.parserFunc(r)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
+		_, _ = w.Write([]byte(err.Error()))
+	} else {
+		// send message to xmpp client
+		h.messages <- m
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
 	}
-	// send message to xmpp client
-	h.messages <- m
-	w.WriteHeader(response.Code)
-	w.Write([]byte(response.Message))
 }
 
 // returns new handler with a given parser function
@@ -43,98 +34,3 @@ func newMessageHandler(m chan<- string, f parserFunc) *messageHandler {
 		parserFunc: f,
 	}
 }
-
-/*************
-GRAFANA PARSER
-*************/
-func grafanaParserFunc(r *http.Request) (string, error, Response) {
-	// get alert data from request
-	body, err := ioutil.ReadAll(r.Body)
-	if err != nil {
-		return "", err, errorResponse()
-	}
-
-	// grafana alert struct
-	alert := &struct {
-		Title   string `json:"title"`
-		RuleURL string `json:"ruleUrl"`
-		State   string `json:"state"`
-		Message string `json:"message"`
-	}{}
-
-	// parse body into the alert struct
-	err = json.Unmarshal(body, &alert)
-	if err != nil {
-		return "", err, errorResponse()
-	}
-
-	// contruct alert message
-	var message string
-	switch alert.State {
-	case "ok":
-		message = ":) " + alert.Title
-	default:
-		message = ":( " + alert.Title + "\n" + alert.Message + "\n" + alert.RuleURL
-	}
-
-	return message, nil, Response{"", http.StatusNoContent}
-}
-
-/*************
-SLACK PARSER
-*************/
-type SlackMessage struct {
-	Channel     string            `json:"channel"`
-	IconEmoji   string            `json:"icon_emoji"`
-	Username    string            `json:"username"`
-	Text        string            `json:"text"`
-	Attachments []SlackAttachment `json:"attachments"`
-}
-
-type SlackAttachment struct {
-	Color     string `json:"color"`
-	Title     string `json:"title"`
-	TitleLink string `json:"title_link"`
-	Text      string `json:"text"`
-}
-
-func nonemptyAppendNewline(message string) string {
-	if len(message) == 0 {
-		return message
-	}
-
-	return message + "\n"
-}
-
-func slackParserFunc(r *http.Request) (string, error, Response) {
-	// get alert data from request
-	body, err := ioutil.ReadAll(r.Body)
-	if err != nil {
-		return "", err, errorResponse()
-	}
-
-	// grafana alert struct
-	alert := SlackMessage{}
-
-	// parse body into the alert struct
-	err = json.Unmarshal(body, &alert)
-	if err != nil {
-		return "", err, Response{"", http.StatusInternalServerError}
-	}
-
-	// contruct alert message
-	message := ""
-	hasText := (alert.Text != "")
-	if hasText {
-		message = alert.Text
-	}
-
-	for _, attachment := range alert.Attachments {
-		message = nonemptyAppendNewline(message)
-		message += attachment.Title + "\n"
-		message += attachment.TitleLink + "\n\n"
-		message += attachment.Text
-	}
-
-	return message, nil, Response{"ok", http.StatusOK}
-}

main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/tls"
 	"encoding/xml"
+	"github.com/opthomas-prime/xmpp-webhook/parser"
 	"io"
 	"log"
 	"mellium.im/sasl"
@@ -79,11 +80,11 @@ func main() {
 		log.Fatal("XMPP_ID, XMPP_PASS or XMPP_RECEIVERS not set")
 	}
 
-	address, err := jid.Parse(xi)
+	myjid, err := jid.Parse(xi)
 	panicOnErr(err)
 
 	// connect to xmpp server
-	xmppSession, err := initXMPP(address, xp, skipTLSVerify, useXMPPS)
+	xmppSession, err := initXMPP(myjid, xp, skipTLSVerify, useXMPPS)
 	panicOnErr(err)
 	defer closeXMPP(xmppSession)
 
@@ -115,7 +116,7 @@ func main() {
 			reply := MessageBody{
 				Message: stanza.Message{
 					To:   msg.From.Bare(),
-					From: address,
+					From: myjid,
 					Type: stanza.ChatMessage,
 				},
 				Body: msg.Body,
@@ -141,7 +142,7 @@ func main() {
 				_ = xmppSession.Encode(MessageBody{
 					Message: stanza.Message{
 						To:   recipient,
-						From: address,
+						From: myjid,
 						Type: stanza.ChatMessage,
 					},
 					Body: m,
@@ -150,9 +151,9 @@ func main() {
 		}
 	}()
 
-	// initialize handler for grafana alerts
-	http.Handle("/grafana", newMessageHandler(messages, grafanaParserFunc))
-	http.Handle("/slack", newMessageHandler(messages, slackParserFunc))
+	// initialize handlers with accociated parser functions
+	http.Handle("/grafana", newMessageHandler(messages, parser.GrafanaParserFunc))
+	http.Handle("/slack", newMessageHandler(messages, parser.SlackParserFunc))
 
 	// listen for requests
 	_ = http.ListenAndServe(":4321", nil)

parser/common.go

@@ -0,0 +1,4 @@
+package parser
+
+const readErr string = "failed to read alert body"
+const parseErr string = "failed to parse alert body"

parser/grafana.go

@@ -0,0 +1,42 @@
+package parser
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+)
+
+func GrafanaParserFunc(r *http.Request) (string, error) {
+	// get alert data from request
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return "", errors.New(readErr)
+	}
+
+	alert := &struct {
+		Title   string `json:"title"`
+		RuleURL string `json:"ruleUrl"`
+		State   string `json:"state"`
+		Message string `json:"message"`
+	}{}
+
+	// parse body into the alert struct
+	err = json.Unmarshal(body, &alert)
+	if err != nil {
+		return "", errors.New(parseErr)
+	}
+
+	// contruct alert message
+	var message string
+	switch alert.State {
+	case "ok":
+		message = ":) " + alert.Title
+	default:
+		message = ":( " + alert.Title + "\n\n"
+		message += alert.Message + "\n\n"
+		message += alert.RuleURL
+	}
+
+	return message, nil
+}

parser/slack-compatible.go

@@ -0,0 +1,44 @@
+package parser
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+)
+
+func SlackParserFunc(r *http.Request) (string, error) {
+	// get alert data from request
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return "", errors.New(readErr)
+	}
+
+	alert := struct {
+		Text        string `json:"text"`
+		Attachments []struct {
+			Title     string `json:"title"`
+			TitleLink string `json:"title_link"`
+			Text      string `json:"text"`
+		} `json:"attachments"`
+	}{}
+
+	// parse body into the alert struct
+	err = json.Unmarshal(body, &alert)
+	if err != nil {
+		return "", errors.New(parseErr)
+	}
+
+	// contruct alert message
+	message := alert.Text
+	for _, attachment := range alert.Attachments {
+		if len(message) > 0 {
+			message = message + "\n"
+		}
+		message += attachment.Title + "\n"
+		message += attachment.TitleLink + "\n\n"
+		message += attachment.Text
+	}
+
+	return message, nil
+}