add flags

wrp.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"flag"
 	"fmt"
 	"log"
 	"net/http"
@@ -82,9 +83,12 @@ func capture(url string, out http.ResponseWriter) {
 func main() {
 	ctx, cancel = chromedp.NewContext(context.Background())
 	defer cancel()
+	var addr string
+	flag.StringVar(&addr, "l", ":8080", "Listen address:port, default :8080")
+	flag.Parse()
 
 	http.HandleFunc("/", pageServer)
 	http.HandleFunc("/wrp.png", imgServer)
-    log.Printf("Starting http server on :8080\n")
-    http.ListenAndServe(":8080", nil)
+	log.Printf("Starting http server on %s\n", addr)
+	http.ListenAndServe(addr, nil)
 }