allow port to be configured with direct assignment

app.go

@@ -66,6 +66,8 @@ type Node struct {
 	// Hostname is the hostname to use when registering the node.
 	Hostname string `json:"hostname,omitempty" caddy:"namespace=tailscale.hostname"`
 
+	Port uint16 `json:"port,omitempty" caddy:"namespace=tailscale.port"`
+
 	// StateDir specifies the state directory for the node.
 	StateDir string `json:"state_dir,omitempty" caddy:"namespace=tailscale.state_dir"`
 
@@ -190,6 +192,17 @@ func parseNodeConfig(d *caddyfile.Dispenser) (Node, error) {
 			} else {
 				node.Ephemeral = opt.NewBool(true)
 			}
+		case "port":
+			if segment.NextArg() {
+				v, err := strconv.ParseUint(segment.Val(), 10, 16)
+				if err != nil {
+					return node, segment.WrapErr(err)
+				}
+				node.Port = uint16(v)
+			} else {
+				node.Port = 0
+			}
+
 		case "hostname":
 			if !segment.NextArg() {
 				return node, segment.ArgErr()

module.go

@@ -49,12 +49,12 @@ func getTCPListener(c context.Context, network string, host string, portRange st
 	if !ok {
 		return nil, fmt.Errorf("context is not a caddy.Context: %T", c)
 	}
-	
+
 	na, err := caddy.ParseNetworkAddress(caddy.JoinNetworkAddress(network, host, portRange))
 	if err != nil {
 		return nil, err
 	}
-	
+
 	addr := na.JoinHostPort(portOffset)
 	network, host, port, err := caddy.SplitNetworkAddress(addr)
 	if err != nil {
@@ -82,7 +82,7 @@ func getTLSListener(c context.Context, network string, host string, portRange st
 	if err != nil {
 		return nil, err
 	}
-	
+
 	addr := na.JoinHostPort(portOffset)
 	network, host, port, err := caddy.SplitNetworkAddress(addr)
 	if err != nil {
@@ -121,7 +121,7 @@ func getUDPListener(c context.Context, network string, host string, portRange st
 	if err != nil {
 		return nil, err
 	}
-	
+
 	addr := na.JoinHostPort(portOffset)
 	network, host, port, err := caddy.SplitNetworkAddress(addr)
 	if err != nil {
@@ -183,6 +183,7 @@ func getNode(ctx caddy.Context, name string) (*tailscaleNode, error) {
 			},
 			Ephemeral:    getEphemeral(name, app),
 			RunWebClient: getWebUI(name, app),
+			Port:         getPort(name, app),
 		}
 
 		if s.AuthKey, err = getAuthKey(name, app); err != nil {
@@ -268,6 +269,14 @@ func getHostname(name string, app *App) (string, error) {
 	return name, nil
 }
 
+func getPort(name string, app *App) uint16 {
+	if node, ok := app.Nodes[name]; ok {
+		return node.Port
+	}
+
+	return 0
+}
+
 func getStateDir(name string, app *App) (string, error) {
 	if node, ok := app.Nodes[name]; ok {
 		if node.StateDir != "" {

module_test.go

@@ -221,6 +221,34 @@ func Test_GetHostname(t *testing.T) {
 	}
 }
 
+func Test_GetPort(t *testing.T) {
+	app := &App{
+		Nodes: map[string]Node{
+			"empty": {},
+			"port":  {Port: 3000},
+		},
+	}
+	if err := app.Provision(caddy.Context{}); err != nil {
+		t.Fatal(err)
+	}
+
+	got := getPort("noconfig", &App{})
+	if want := uint16(0); got != want {
+		t.Errorf("GetPort() = %v, want %v", got, want)
+	}
+
+	got = getPort("empty", app)
+	if want := uint16(0); got != want {
+		t.Errorf("GetPort() = %v, want %v", got, want)
+	}
+
+	got = getPort("port", app)
+	if want := uint16(3000); got != want {
+		t.Errorf("GetPort() = %v, want %v", got, want)
+	}
+
+}
+
 func Test_GetStateDir(t *testing.T) {
 	const nodeName = "node"
 	configDir := must.Get(os.UserConfigDir())