notify/telegram: Set API and ParseMode defaults

Signed-off-by: Matthias Loibl <mail@matthiasloibl.com>

notify/telegram/telegram.go

@@ -16,6 +16,7 @@ package telegram
 import (
 	"context"
 	"net/http"
+	"net/url"
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
@@ -44,6 +45,19 @@ func New(conf *config.TelegramConfig, t *template.Template, l log.Logger, httpOp
 		return nil, err
 	}
 
+	if conf.APIUrl == nil {
+		apiURL, err := url.Parse("https://api.telegram.org")
+		if err != nil {
+			return nil, err
+		}
+		conf.APIUrl = &config.URL{URL: apiURL}
+	}
+	if conf.ParseMode == "" {
+		// The default Telegram template is in HTML,
+		// so we need to set the parse mode to HTML for Telegram not to return a parse error.
+		conf.ParseMode = "HTML"
+	}
+
 	client, err := createTelegramClient(conf.BotToken, conf.APIUrl.String(), conf.ParseMode, httpclient)
 	if err != nil {
 		return nil, err