Golang webserver with ip and request logging

webserver.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httputil"
	"flag"
	"strings"
	"os"
)

func main() {
	var httpPort int
	var serverDir string
	var verbose bool

	flag.IntVar(&httpPort, "p", 80, "port to listen on")
	flag.StringVar(&serverDir, "d", "web", "Directory to serve files from")
	flag.BoolVar(&verbose, "v", false, "Verbose mode")
	flag.Parse()

	if _, err := os.Stat(serverDir); os.IsNotExist(err) {
		log.Fatalf("Diretory %v does not exists",serverDir)
	}


	log.SetOutput(os.Stdout)

	http.Handle("/", http.FileServer(http.Dir(serverDir)))
	log.Println("Verbose enabled?", verbose)
	log.Println("Logging to Stdout. If you need file logs, tee the output (ie. './webserver | tee -a server.log')")
	log.Println("Alternatively, log full output to log file and only minimal output to stdout: ./webserver -p 9999 -v | tee server.log | grep \"^2023\" --line-buffered | egrep -v \"Request Dump\"")
	log.Printf("Listening on %v and serving from the %v folder\n", httpPort, serverDir)

	err := http.ListenAndServe(fmt.Sprintf(":%d", httpPort), logRequest(http.DefaultServeMux, verbose))
	if err != nil {
		log.Fatal(err)
	}
}

func logRequest(handler http.Handler, verbose bool) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {


		ipAddress := r.RemoteAddr
		fwdAddress := r.Header.Get("X-Forwarded-For") // capitalisation doesn't matter
		if fwdAddress != "" {
			// Got X-Forwarded-For
			ipAddress = fwdAddress // If it's a single IP, then awesome!

			// If we got an array... grab the first IP
			ips := strings.Split(fwdAddress, ", ")
			if len(ips) > 1 {
				ipAddress = ips[0]
			}
		}

		log.Printf("%s %s %s %s\n", ipAddress, r.RemoteAddr, r.Method, r.URL)
		if verbose {
            // change to true if you want the Request body as well
			dump, err := httputil.DumpRequest(r, false)
			if err != nil {
				log.Println("Error while dumping above request", err) 
			} else {
				log.Printf("Request Dump:\n%s\n",dump)
			}

		}
		handler.ServeHTTP(w, r)
	})
}