Spawns file server of current directory on a random port and configures firewall for it.

RandomFileServer.go

package main

import (
	"context"
	"log"
	"math/rand"
	"net/http"
	"os"
	"os/exec"
	"os/signal"
	"strconv"
	"syscall"
	"time"
)

func main(){
	rand.Seed(time.Now().Unix())

	port := strconv.Itoa(rand.Intn(65535) + 1)
	srv := &http.Server{
		Addr:    ":" + port,
		Handler: http.FileServer( http.Dir( "." )),
	}

	cmd := exec.Command("ufw", "allow", port + "/tcp") // you have to change this
	stdout, err := cmd.Output()

	if err != nil {
		log.Fatal(err.Error())
	}
	log.Print("Firewall status: ", string(stdout))

	// https://medium.com/honestbee-tw-engineer/gracefully-shutdown-in-go-http-server-5f5e6b83da5a
	done := make(chan os.Signal, 1)
	signal.Notify(done, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("listen: %s\n", err)
		}
	}()
	log.Print("Server started on 127.0.0.1:", port) // you can change the IP of server
	<-done
	log.Print("Server Stopped")

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer func() {
		cmd := exec.Command("ufw","delete", "allow", port + "/tcp") // you have to change this
		stdout, err := cmd.Output()

		if err != nil {
			log.Print("Cannot delete firewall rules: ",err.Error())
		}else {
			log.Print("Firewall delete port status: ", string(stdout))
		}
		cancel()
	}()

	if err := srv.Shutdown(ctx); err != nil {
		log.Fatalf("Server Shutdown Failed:%+v", err)
	}else {
		log.Print("Server Exited Properly")
	}
}