Go HTTP server to show if client request is working as expected.

main.go

package main

import (
	"fmt"
	"io"
	"net/http"
	"os"
)

func defaultHandler(res http.ResponseWriter, req *http.Request) {
	body, err := io.ReadAll(req.Body)
	if err != nil {
		fmt.Fprintf(res, "error parsing body : %s", err)
		return
	}

	response := req.Method + " " + req.URL.Path
	response += "\nheaders: " + fmt.Sprintf("%v", req.Header)
	response += "\nbody: " + string(body)

	fmt.Println(response)
	fmt.Fprintf(res, response)
}

func main() {
	http.HandleFunc("/", defaultHandler)

	port := "8080"
	if len(os.Args) > 1 {
		port = os.Args[1]
	}
	fmt.Print("listening on http://localhost:", port)

	err := http.ListenAndServe(":"+port, nil)
	if err != nil {
		panic(err)
	}
}