Go server with automatic Let's Encrypt registration and graceful restarts

server.go

package main

import (
	"crypto/tls"
	"github.com/facebookgo/grace/gracehttp"
	"log"
	"net/http"
	"rsc.io/letsencrypt"
)

func main() {
	var m letsencrypt.Manager

	if err := m.CacheFile("letsencrypt.cache"); err != nil {
		log.Fatal(err)
	}

	httpServer := &http.Server{
		Addr:    ":http",
		Handler: http.HandlerFunc(letsencrypt.RedirectHTTP),
	}

	httpsServer := &http.Server{
		Addr: ":https",
		Handler: http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
			rw.Write([]byte("OK"))
		}),
		TLSConfig: &tls.Config{
			GetCertificate: m.GetCertificate,
		},
	}

	if err := gracehttp.Serve(httpServer, httpsServer); err != nil {
		log.Fatal(err)
	}
}