tls_example.go

package main

import (
        "context"
        "crypto/tls"
        "fmt"
        "log"
        "net/http"
        "os"
        "strings"

        "golang.org/x/crypto/acme/autocert"
)

func main() {
        addr := ":" + os.Getenv("PORT")

        router := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
                if r.URL.Path == "/health" {
                        w.Write([]byte("ok"))
                } else {
                        // I pass this to a router from another package
                        // Do whatever you want
                        w.Write([]byte("Hello World"))
                }
        })

        certMgr := autocert.Manager{
                Prompt: func(_ string) bool {
                        return true
                },
                HostPolicy: func(_ context.Context, host string) error {
                        if strings.Contains(host, os.Getenv("DOMAIN")) {
                                return nil
                        } else {
                                return fmt.Errorf("Domain not valid")
                        }
                },
        }
        s := &http.Server{
                Handler: certMgr.HTTPHandler(router),
                Addr:    addr,
        }

        log.Printf("INFO Listening on: %s", addr)
        go func() {
                log.Fatal(s.ListenAndServe())
        }()

        s2 := &http.Server{
                Handler:   router,
                Addr:      ":https",
                TLSConfig: &tls.Config{GetCertificate: certMgr.GetCertificate},
        }

        log.Printf("INFO Listening on 443 with TLS")
        log.Fatal(s2.ListenAndServeTLS("", ""))
}