client/web: add web client Server struct

Updates tailscale/corp#13775

Signed-off-by: Sonia Appasamy <sonia@tailscale.com>

cmd/tailscale/cli/web.go

@@ -38,6 +38,7 @@ Tailscale, as opposed to a CLI or a native app.
 		webf := newFlagSet("web")
 		webf.StringVar(&webArgs.listen, "listen", "localhost:8088", "listen address; use port 0 for automatic")
 		webf.BoolVar(&webArgs.cgi, "cgi", false, "run as CGI script")
+		webf.BoolVar(&webArgs.dev, "dev", false, "run web client in developer mode")
 		return webf
 	})(),
 	Exec: runWeb,
@@ -46,6 +47,7 @@ Tailscale, as opposed to a CLI or a native app.
 var webArgs struct {
 	listen string
 	cgi    bool
+	dev    bool
 }
 
 func tlsConfigFromEnvironment() *tls.Config {
@@ -76,10 +78,10 @@ func runWeb(ctx context.Context, args []string) error {
 		return fmt.Errorf("too many non-flag arguments: %q", args)
 	}
 
-	webHandler := http.HandlerFunc(web.Handle)
+	webServer := web.NewServer(webArgs.dev, nil)
 
 	if webArgs.cgi {
-		if err := cgi.Serve(webHandler); err != nil {
+		if err := cgi.Serve(webServer); err != nil {
 			log.Printf("tailscale.cgi: %v", err)
 			return err
 		}
@@ -91,14 +93,14 @@ func runWeb(ctx context.Context, args []string) error {
 		server := &http.Server{
 			Addr:      webArgs.listen,
 			TLSConfig: tlsConfig,
-			Handler:   webHandler,
+			Handler:   webServer,
 		}
 
 		log.Printf("web server running on: https://%s", server.Addr)
 		return server.ListenAndServeTLS("", "")
 	} else {
 		log.Printf("web server running on: %s", urlOfListenAddr(webArgs.listen))
-		return http.ListenAndServe(webArgs.listen, webHandler)
+		return http.ListenAndServe(webArgs.listen, webServer)
 	}
 }