New feature: Telegram Notifier (#2503)

Co-authored-by: Tom Limoncelli <tlimoncelli@stackoverflow.com>

documentation/notifications.md

@@ -82,6 +82,12 @@ Please see the [Teams documentation](https://docs.microsoft.com/en-us/microsoftt
 
 Configure `teams_url` to this webhook.
 
+### Telegram
+
+If you want to use the [Telegram](https://telegram.org/) integration, you need to create a Telegram bot and obtain a Bot Token, as well as a Chat ID. Get a Bot Token by contacting [@BotFather](https://telegram.me/botfather), and a Chat ID by contacting [@myidbot](https://telegram.me/myidbot).
+
+Configure `telegram_bot_token` and `telegram_chat_id` to these values.
+
 ### Bonfire
 
 This is Stack Overflow's built in chat system. This is probably not useful for most people.

pkg/notifications/telegram.go

@@ -0,0 +1,56 @@
+package notifications
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+)
+
+func init() {
+	initers = append(initers, func(cfg map[string]string) Notifier {
+		if bot_token, ok := cfg["telegram_bot_token"]; ok {
+			if chat_id, ok := cfg["telegram_chat_id"]; ok {
+				notifier := &telegramNotifier{
+					BOT_TOKEN: bot_token,
+					CHAT_ID:   chat_id,
+				}
+				return notifier
+			}
+		}
+		return nil
+	})
+}
+
+// telegramNotifier sends notifications to Telegram
+type telegramNotifier struct {
+	BOT_TOKEN string
+	CHAT_ID   string
+}
+
+func (s *telegramNotifier) Notify(domain, provider, msg string, err error, preview bool) {
+	var payload struct {
+		ChatID int64  `json:"chat_id"`
+		Text   string `json:"text"`
+	}
+
+	var url = fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage", s.BOT_TOKEN)
+
+	payload.ChatID, _ = strconv.ParseInt(s.CHAT_ID, 10, 64)
+
+	if preview {
+		payload.Text = fmt.Sprintf(`DNSControl preview: %s[%s] -** %s`, domain, provider, msg)
+	} else if err != nil {
+		payload.Text = fmt.Sprintf(`DNSControl ERROR running correction on %s[%s] -** (%s) Error: %s`, domain, provider, msg, err)
+	} else {
+		payload.Text = fmt.Sprintf(`DNSControl successfully ran correction for **%s[%s]** - %s`, domain, provider, msg)
+	}
+
+	marshaled_payload, _ := json.Marshal(payload)
+
+	_, _ = http.Post(url, "application/json", bytes.NewBuffer(marshaled_payload))
+
+}
+
+func (s *telegramNotifier) Done() {}