package main
import (
    "net/http"
)

func redirect(w http.ResponseWriter, req *http.Request) {
    http.Redirect(w, req,
            "https://" + req.Host + req.URL.String(),
            http.StatusMovedPermanently)
}

func index(w http.ResponseWriter, req *http.Request) {
    // all calls to unknown url paths should return 404
    if req.URL.Path != "/" {
        http.NotFound(w, req)
        return
    }
    http.ServeFile(w, req, "index.html")
}

func main() {
    // redirect every http request to https
    go http.ListenAndServe(":80", http.HandlerFunc(redirect))
    // serve index (and anything else) as https
    mux := http.NewServeMux()
    mux.HandleFunc("/", index)
    http.ListenAndServeTLS(":443", "cert.pem", "key.pem", mux)
}