HTTP File Server in Golang

serve.go

package main

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

func getenvWithDefault(key, fallback string) string {
	value := os.Getenv(key)
	if len(value) == 0 {
		return fallback
	}
	return value
}

func main() {
	port := getenvWithDefault("PORT", "8080")
	host := getenvWithDefault("HOST", "")
	listen := fmt.Sprint(host, ":", port)
	fmt.Println("Listening on:", listen)
	log.Fatal(http.ListenAndServe(listen, http.FileServer(http.Dir("."))))
}