golang-auto-https.go

package main

import (
	"crypto/tls"
	"fmt"
	"golang.org/x/crypto/acme/autocert"
	"log"
	"net/http"
	"os"
)

func main() {
	// setup a simple handler which sends a HTHS header for six months (!)
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Strict-Transport-Security", "max-age=15768000 ; includeSubDomains")
		fmt.Fprintf(w, "Hello, HTTPS world!")
	})

	// create the autocert.Manager with domains and path to the cache
	certManager := autocert.Manager{
		Prompt:     autocert.AcceptTOS,
		HostPolicy: autocert.HostWhitelist(os.Getenv("DOMAIN")),
		Cache:      autocert.DirCache("."),
	}

	// create the server itself
	server := &http.Server{
		Addr: ":https",
		TLSConfig: &tls.Config{
			GetCertificate: certManager.GetCertificate,
		},
	}

	log.Printf("Serving http/https for domains: %+v", os.Getenv("DOMAIN"))
	go func() {
		// serve HTTP, which will redirect automatically to HTTPS
		h := certManager.HTTPHandler(nil)
		log.Fatal(http.ListenAndServe(":http", h))
	}()

	// serve HTTPS!
	log.Fatal(server.ListenAndServeTLS("", ""))
}