Update app and tooling

node_modules/@vercel/go/dev-server.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"io/ioutil"
+	"net"
+	"net/http"
+	"os"
+	"strconv"
+)
+
+func main() {
+	// create a new handler
+	handler := http.HandlerFunc(__HANDLER_FUNC_NAME)
+
+	// https://stackoverflow.com/a/43425461/376773
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		panic(err)
+	}
+
+	port := listener.Addr().(*net.TCPAddr).Port
+	portBytes := []byte(strconv.Itoa(port))
+
+	file := os.NewFile(3, "pipe")
+	_, err2 := file.Write(portBytes)
+	if err2 != nil {
+		portFile := os.Getenv("VERCEL_DEV_PORT_FILE")
+		os.Unsetenv("VERCEL_DEV_PORT_FILE")
+		err3 := ioutil.WriteFile(portFile, portBytes, 0644)
+		if err3 != nil {
+			panic(err3)
+		}
+	}
+
+	panic(http.Serve(listener, handler))
+}