add commmandline flags

serve.go

@@ -1,7 +1,38 @@
 package main
 
-import "fmt"
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "\nusage: go run serve.go [optional flags]\n")
+	flag.PrintDefaults()
+	fmt.Println()
+
+	os.Exit(2)
+}
 
 func main() {
-	fmt.Println("Hello, World!")
+	flag.Usage = usage
+
+	port := flag.Uint("port", 443, "https port")
+	certsPath := flag.String("letsencrypt-path", "/etc/letsencrypt/live", "path at which an 'xyz.example.com' containing 'fullchain.pem' and 'privkey.pem' can be found")
+	defaultHost := flag.String("default-hostname", "localhost.daplie.com", "the default folder to find certificates to use when no matches are found")
+
+	flag.Parse()
+
+	host := strings.ToLower(*defaultHost)
+	// See https://groups.google.com/a/letsencrypt.org/forum/#!topic/ca-dev/l1Dd6jzWeu8
+	/*
+		if strings.HasPrefix("www.", host) {
+			fmt.Println("Because www.example.com is also example.com")
+		}
+		host = strings.TrimPrefix("www.", host)
+	*/
+
+	fmt.Printf("Loading Certificates %s/%s/{privkey.pem,fullchain.pem}\n", *certsPath, *defaultHost)
+	fmt.Printf("Listening on https://%s:%d\n", host, *port)
 }