fix(pia): set port forward file owned with PUID and PGID

cmd/gluetun/main.go

@@ -347,7 +347,7 @@ func _main(ctx context.Context, buildInfo models.BuildInformation,
 
 	portForwardLogger := logger.New(log.SetComponent("port forwarding"))
 	portForwardLooper := portforward.NewLoop(allSettings.VPN.Provider.PortForwarding,
-		httpClient, firewallConf, portForwardLogger)
+		httpClient, firewallConf, portForwardLogger, puid, pgid)
 	portForwardHandler, portForwardCtx, portForwardDone := goshutdown.NewGoRoutineHandler(
 		"port forwarding", goroutine.OptionTimeout(time.Second))
 	go portForwardLooper.Run(portForwardCtx, portForwardDone)

internal/portforward/fs.go

@@ -16,22 +16,22 @@ func (l *Loop) removePortForwardedFile() {
 func (l *Loop) writePortForwardedFile(port uint16) {
 	filepath := *l.state.GetSettings().Filepath
 	l.logger.Info("writing port file " + filepath)
-	if err := writePortForwardedToFile(filepath, port); err != nil {
-		l.logger.Error(err.Error())
+	if err := writePortForwardedToFile(filepath, port, l.puid, l.pgid); err != nil {
+		l.logger.Error("writing port forwarded to file: " + err.Error())
 	}
 }
 
-func writePortForwardedToFile(filepath string, port uint16) (err error) {
-	file, err := os.OpenFile(filepath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
+func writePortForwardedToFile(filepath string, port uint16, uid, gid int) (err error) {
+	const perms = os.FileMode(0644)
+	err = os.WriteFile(filepath, []byte(fmt.Sprint(port)), perms)
 	if err != nil {
-		return err
+		return fmt.Errorf("writing file: %w", err)
 	}
 
-	_, err = file.Write([]byte(fmt.Sprint(port)))
+	err = os.Chown(filepath, uid, gid)
 	if err != nil {
-		_ = file.Close()
-		return err
+		return fmt.Errorf("chowning file: %w", err)
 	}
 
-	return file.Close()
+	return nil
 }

internal/portforward/loop.go

@@ -15,6 +15,9 @@ import (
 type Loop struct {
 	statusManager *loopstate.State
 	state         *state.State
+	// Fixed parameters
+	puid int
+	pgid int
 	// Objects
 	client      *http.Client
 	portAllower PortAllower
@@ -33,7 +36,7 @@ const defaultBackoffTime = 5 * time.Second
 
 func NewLoop(settings settings.PortForwarding,
 	client *http.Client, portAllower PortAllower,
-	logger Logger) *Loop {
+	logger Logger, puid, pgid int) *Loop {
 	start := make(chan struct{})
 	running := make(chan models.LoopStatus)
 	stop := make(chan struct{})
@@ -45,6 +48,8 @@ func NewLoop(settings settings.PortForwarding,
 	return &Loop{
 		statusManager: statusManager,
 		state:         state,
+		puid:          puid,
+		pgid:          pgid,
 		// Objects
 		client:      client,
 		portAllower: portAllower,