make tunnel timeout configurable

builder/googlecompute/config.go

@@ -425,6 +425,9 @@ func (c *Config) Prepare(raws ...interface{}) ([]string, error) {
 			c.IAPConfig.IAPExt = ".cmd"
 		}
 	}
+	if c.IAPConfig.IAPTunnelLaunchTimeout == 0 {
+		c.IAPConfig.IAPTunnelLaunchTimeout = 30
+	}
 
 	// Configure IAP: Update SSH config to use localhost proxy instead
 	if c.IAPConfig.IAP {

builder/googlecompute/step_start_tunnel.go

@@ -51,14 +51,17 @@ type IAPConfig struct {
 	// What file extension to use for script that sets up gcloud.
 	// Default: ".sh"
 	IAPExt string `mapstructure:"iap_ext" required:"false"`
+	// How long to wait, in seconds, before assuming a tunnel launch was
+	// successful. Defaults to 30 seconds.
+	IAPTunnelLaunchTimeout int `mapstructure:"iap_tunnel_launch_timeout" required:"false"`
 }
 
 type TunnelDriver interface {
-	StartTunnel(context.Context, string) error
+	StartTunnel(context.Context, string, int) error
 	StopTunnel()
 }
 
-func RunTunnelCommand(cmd *exec.Cmd) error {
+func RunTunnelCommand(cmd *exec.Cmd, timeout int) error {
 	// set stdout and stderr so we can read what's going on.
 	var stdout, stderr bytes.Buffer
 	cmd.Stdout = &stdout
@@ -78,7 +81,8 @@ func RunTunnelCommand(cmd *exec.Cmd) error {
 	// afternoon trying to figure out how to get the SDK to actually send
 	// the "Listening on port [n]" line I see when I run it manually, and I
 	// can't justify spending more time than that on aesthetics.
-	for i := 0; i < 30; i++ {
+
+	for i := 0; i < timeout; i++ {
 		time.Sleep(1 * time.Second)
 
 		lineStderr, err := stderr.ReadString('\n')
@@ -307,7 +311,7 @@ func (s *StepStartTunnel) Run(ctx context.Context, state multistep.StateBag) mul
 		RetryDelay: (&retry.Backoff{InitialBackoff: 200 * time.Millisecond, MaxBackoff: 30 * time.Second, Multiplier: 2}).Linear,
 	}.Run(ctx, func(ctx context.Context) error {
 		// tunnel launcher/destroyer has to be different on windows vs. unix.
-		err := s.tunnelDriver.StartTunnel(ctx, tempScriptFileName)
+		err := s.tunnelDriver.StartTunnel(ctx, tempScriptFileName, s.IAPConf.IAPTunnelLaunchTimeout)
 		return err
 	})
 	if err != nil {

builder/googlecompute/step_start_tunnel_test.go

@@ -14,14 +14,16 @@ import (
 type MockTunnelDriver struct {
 	StopTunnelCalled   bool
 	StartTunnelCalled  bool
+	StartTunnelTimeout int
 }
 
 func (m *MockTunnelDriver) StopTunnel() {
 	m.StopTunnelCalled = true
 }
 
-func (m *MockTunnelDriver) StartTunnel(context.Context, string) error {
+func (m *MockTunnelDriver) StartTunnel(_ context.Context, _ string, timeout int) error {
 	m.StartTunnelCalled = true
+	m.StartTunnelTimeout = timeout
 	return nil
 }
 

builder/googlecompute/tunnel_driver.go

@@ -17,11 +17,11 @@ type TunnelDriverLinux struct {
 	cmd *exec.Cmd
 }
 
-func (t *TunnelDriverLinux) StartTunnel(cancelCtx context.Context, tempScriptFileName string) error {
+func (t *TunnelDriverLinux) StartTunnel(cancelCtx context.Context, tempScriptFileName string, timeout int) error {
 	cmd := exec.CommandContext(cancelCtx, tempScriptFileName)
 	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
 
-	err := RunTunnelCommand(cmd)
+	err := RunTunnelCommand(cmd, timeout)
 	if err != nil {
 		return err
 	}

builder/googlecompute/tunnel_driver_windows.go

@@ -16,10 +16,10 @@ type TunnelDriverWindows struct {
 	cmd *exec.Cmd
 }
 
-func (t *TunnelDriverWindows) StartTunnel(cancelCtx context.Context, tempScriptFileName string) error {
+func (t *TunnelDriverWindows) StartTunnel(cancelCtx context.Context, tempScriptFileName string, timeout int) error {
 	args := []string{"/C", "call", tempScriptFileName}
 	cmd := exec.CommandContext(cancelCtx, "cmd", args...)
-	err := RunTunnelCommand(cmd)
+	err := RunTunnelCommand(cmd, timeout)
 	if err != nil {
 		return err
 	}