http -> https

package main

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

var httpAddr ":8080"
var httpsAddr ":8443"

func main() {
    srv := http.Server{
        Addr: httpsAddr,
    }

    _, tlsPort, err := net.SplitHostPort(httpsAddr)
    if err != nil {
        return err
    }
    go redirectToHTTPS(tlsPort)

    srv.ListenAndServeTLS("cert.pem", "key.pem")
}

func redirectToHTTPS(tlsPort string) {
    httpSrv := http.Server{
        Addr: httpAddr,
        Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request){
            var host string
		if strings.Contains(r.Host, ":") {
			var err error
			host, _, err = net.SplitHostPort(r.Host)
			if err != nil {
				panic(err)
			}
	      } else {
				host = r.Host
	      }
            u := r.URL
            u.Host = net.JoinHostPort(host, tlsPort)
            u.Scheme="https"
            log.Println(u.String())
            http.Redirect(w,r,u.String(), http.StatusMovedPermanently)
        }),
    }
    log.Println(httpSrv.ListenAndServe())
}