fix: delay initialization by default

README.md

@@ -18,5 +18,6 @@ transmission-gluetun-port -h
 | `TRANSMISSION_PASSWORD` | Transmission password | - |
 | `GLUETUN_HOST` | Gluetun api host | `127.0.0.1` |
 | `GLUETUN_PORT` | Gluetun api port | `8000` |
+| `INITIAL_DELAY` | Initial delay ([format](https://pkg.go.dev/time#ParseDuration)) | `5s` |
 | `CHECK_INTERVAL` | Update interval ([format](https://pkg.go.dev/time#ParseDuration)) | `1m` |
 | `ERROR_INTERVAL` | Update interval in case of error ([format](https://pkg.go.dev/time#ParseDuration)) | `5s` |

main.go

@@ -26,6 +26,7 @@ var (
 	gluetunHostname = getEnv("GLUETUN_HOSTNAME", "127.0.0.1")
 	gluetunPort     = getEnv("GLUETUN_PORT", "8000")
 
+	initialDelayStr  = getEnv("INITIAL_DELAY", "5s")
 	checkIntervalStr = getEnv("CHECK_INTERVAL", "1m")
 	errorIntervalStr = getEnv("ERROR_INTERVAL", "5s")
 )
@@ -35,13 +36,16 @@ func init() {
 }
 
 func main() {
+	initialDelay, _ := time.ParseDuration(initialDelayStr)
 	checkInterval, _ := time.ParseDuration(checkIntervalStr)
 	errorInterval, _ := time.ParseDuration(errorIntervalStr)
 	previousExternalPort := uint16(0)
 	gluetunPortApi := fmt.Sprintf("http://%s:%s/v1/openvpn/portforwarded", gluetunHostname, gluetunPort)
 	errorCount := 0
 	maxErrorCount := 5
 
+	time.Sleep(initialDelay)
+
 	httpClient := resty.New()
 
 	transmissionClient, err := transmissionrpc.New(*transmissionHostname, transmissionUsername, transmissionPassword, &transmissionrpc.AdvancedConfig{
@@ -76,9 +80,10 @@ func main() {
 			})
 			if err != nil {
 				log.Fatalf("failed to set transmission peer port: %v", err)
+			} else {
+				previousExternalPort = portMapping.Port
+				log.Printf("updated transmission peer port to: %d", transmissionPeerPort)
 			}
-			previousExternalPort = portMapping.Port
-			log.Printf("updated transmission peer port to: %d", transmissionPeerPort)
 		}
 
 		if err != nil && errorCount < maxErrorCount {