From a35c994bc86c7e37622ba8e4fc1e6e799572e616 Mon Sep 17 00:00:00 2001
From: Quentin McGaw <quentin.mcgaw@gmail.com>
Date: Sat, 22 Nov 2025 23:32:26 +0000
Subject: [PATCH] feat(port-forwarding): add `{{VPN_INTERFACE}}` template
 variable

---
 internal/portforward/service/command.go      | 3 ++-
 internal/portforward/service/command_test.go | 7 ++++---
 internal/portforward/service/start.go        | 2 +-
 internal/portforward/service/stop.go         | 2 +-
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/internal/portforward/service/command.go b/internal/portforward/service/command.go
index f2a20ed9..4d351c25 100644
--- a/internal/portforward/service/command.go
+++ b/internal/portforward/service/command.go
@@ -10,7 +10,7 @@ import (
 )
 
 func runCommand(ctx context.Context, cmder Cmder, logger Logger,
-	commandTemplate string, ports []uint16,
+	commandTemplate string, ports []uint16, vpnInterface string,
 ) (err error) {
 	portStrings := make([]string, len(ports))
 	for i, port := range ports {
@@ -19,6 +19,7 @@ func runCommand(ctx context.Context, cmder Cmder, logger Logger,
 	portsString := strings.Join(portStrings, ",")
 	commandString := strings.ReplaceAll(commandTemplate, "{{PORTS}}", portsString)
 	commandString = strings.ReplaceAll(commandString, "{{PORT}}", portStrings[0])
+	commandString = strings.ReplaceAll(commandString, "{{VPN_INTERFACE}}", vpnInterface)
 	args, err := command.Split(commandString)
 	if err != nil {
 		return fmt.Errorf("parsing command: %w", err)
diff --git a/internal/portforward/service/command_test.go b/internal/portforward/service/command_test.go
index d2747250..2e1e719f 100644
--- a/internal/portforward/service/command_test.go
+++ b/internal/portforward/service/command_test.go
@@ -17,12 +17,13 @@ func Test_Service_runCommand(t *testing.T) {
 
 	ctx := context.Background()
 	cmder := command.New()
-	const commandTemplate = `/bin/sh -c "echo {{PORTS}}"`
+	const commandTemplate = `/bin/sh -c "echo {{PORTS}}-{{PORT}}-{{VPN_INTERFACE}}"`
 	ports := []uint16{1234, 5678}
+	const vpnInterface = "tun0"
 	logger := NewMockLogger(ctrl)
-	logger.EXPECT().Info("1234,5678")
+	logger.EXPECT().Info("1234,5678-1234-tun0")
 
-	err := runCommand(ctx, cmder, logger, commandTemplate, ports)
+	err := runCommand(ctx, cmder, logger, commandTemplate, ports, vpnInterface)
 
 	require.NoError(t, err)
 }
diff --git a/internal/portforward/service/start.go b/internal/portforward/service/start.go
index a13ac0e4..ff3b5248 100644
--- a/internal/portforward/service/start.go
+++ b/internal/portforward/service/start.go
@@ -74,7 +74,7 @@ func (s *Service) Start(ctx context.Context) (runError <-chan error, err error)
 	s.portMutex.Unlock()
 
 	if s.settings.UpCommand != "" {
-		err = runCommand(ctx, s.cmder, s.logger, s.settings.UpCommand, ports)
+		err = runCommand(ctx, s.cmder, s.logger, s.settings.UpCommand, ports, s.settings.Interface)
 		if err != nil {
 			err = fmt.Errorf("running up command: %w", err)
 			s.logger.Error(err.Error())
diff --git a/internal/portforward/service/stop.go b/internal/portforward/service/stop.go
index 085dbcdc..8e86dfc9 100644
--- a/internal/portforward/service/stop.go
+++ b/internal/portforward/service/stop.go
@@ -34,7 +34,7 @@ func (s *Service) cleanup() (err error) {
 		const downTimeout = 60 * time.Second
 		ctx, cancel := context.WithTimeout(context.Background(), downTimeout)
 		defer cancel()
-		err = runCommand(ctx, s.cmder, s.logger, s.settings.DownCommand, s.ports)
+		err = runCommand(ctx, s.cmder, s.logger, s.settings.DownCommand, s.ports, s.settings.Interface)
 		if err != nil {
 			err = fmt.Errorf("running down command: %w", err)
 			s.logger.Error(err.Error())