cmd/dnsupdater/main.go: Add cli flag for config file path

cmd/dnsupdater/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"flag"
 	"os"
 	"time"
 
@@ -11,14 +12,18 @@ import (
 )
 
 func main() {
+	configFile := flag.String("config", "./config.yml", "configuration file")
+
+	flag.Parse()
+
 	log.Logger = log.Output(zerolog.ConsoleWriter{
 		Out:        os.Stderr,
 		TimeFormat: time.RFC3339,
 	})
 
-	config, err := app.LoadConfig("config.yml")
+	config, err := app.LoadConfig(*configFile)
 	if err != nil {
-		log.Fatal().Err(err).Msg("Failed to load config")
+		log.Fatal().Err(err).Str("file", *configFile).Msg("Failed to load config")
 	}
 
 	app, err := app.NewApp(config)
@@ -59,6 +64,5 @@ func main() {
 				}
 			}
 		}
-
 	}
 }