Simple Hello server (need nontrivial functionality to ensure libc usage)

hello-server.go

package main

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

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		defer func() {
			log.Printf(
				"request for %s from %s in %f",
				r.URL.Path,
				r.RemoteAddr,
				time.Since(start))
		}()
		http.Error(w, "Hello there! Everything is 200 OK.", http.StatusOK)
	})
	addr := os.Getenv("ADDR")
	if addr == "" {
		addr = ":4040"
	}
	log.Fatal(http.ListenAndServe(addr, nil))
}