HTTPS

Autocert

package main

import (
    "crypto/tls"
    "fmt"
    "net/http"
    "time"
    "log"

    "github.com/caarlos0/env"
    "github.com/vardius/gorouter/v4"
    "golang.org/x/crypto/acme/autocert"
)

type config struct {
    Host         string   `env:"HOST"              envDefault:"0.0.0.0"`
    Port         int      `env:"PORT"              envDefault:"3000"`
    CertDirCache string   `env:"CERT_DIR_CACHE"`
}

var localHostAddresses = map[string]bool{
    "0.0.0.0":   true,
    "localhost": true,
}

func index(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Hello!\n")
}

func main() {
    cfg := config{}
    env.Parse(&cfg)

    router := gorouter.New()
    router.GET("/", http.HandlerFunc(index))    

    srv := setupServer(&cfg, router)

    log.Fatal(srv.ListenAndServeTLS("", ""))
}

func setupServer(cfg *config, router gorouter.Router) *http.Server {
    srv := &http.Server{
        Addr:         fmt.Sprintf("%s:%d", cfg.Host, cfg.Port),
        ReadTimeout:  5 * time.Second,
        WriteTimeout: 10 * time.Second,
        IdleTimeout:  120 * time.Second,
        Handler:      router,
    }

    // for localhost do not use autocert
    if localHostAddresses[cfg.Host] {
        return srv
    }

    certManager := autocert.Manager{
        Prompt:     autocert.AcceptTOS,
        HostPolicy: autocert.HostWhitelist(cfg.Host),
        Cache:      autocert.DirCache(cfg.CertDirCache),
    }

    tlsConfig := &tls.Config{
        MinVersion:               tls.VersionTLS12,
        CurvePreferences:         []tls.CurveID{tls.CurveP521, tls.CurveP384, tls.CurveP256},
        PreferServerCipherSuites: true,
        CipherSuites: []uint16{
            tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
            tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
            tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
            tls.TLS_RSA_WITH_AES_256_CBC_SHA,
        },
        GetCertificate: certManager.GetCertificate,
    }

    srv.TLSConfig = tlsConfig
    srv.TLSNextProto = make(map[string]func(*http.Server, *tls.Conn, http.Handler), 0)

    return srv
}
Example coming soon...
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