add tls config to server (#1202)

* add tls config

* add TLSConfig to acme provider

server/options.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"context"
+	"crypto/tls"
 	"sync"
 	"time"
 
@@ -39,6 +40,9 @@ type Options struct {
 	// The router for requests
 	Router Router
 
+	// TLSConfig specifies tls.Config for secure serving
+	TLSConfig *tls.Config
+
 	// Other options for implementations of the interface
 	// can be stored in a context
 	Context context.Context
@@ -205,6 +209,19 @@ func RegisterInterval(t time.Duration) Option {
 	}
 }
 
+// TLSConfig specifies a *tls.Config
+func TLSConfig(t *tls.Config) Option {
+	return func(o *Options) {
+		// set the internal tls
+		o.TLSConfig = t
+		// set the transport tls
+		o.Transport.Init(
+			transport.Secure(true),
+			transport.TLSConfig(t),
+		)
+	}
+}
+
 // WithRouter sets the request router
 func WithRouter(r Router) Option {
 	return func(o *Options) {