Switched from NewSingleHostReverseProxy to directly creating ReverseP…

…roxy

main.go

@@ -209,20 +209,20 @@ func main() {
 
 		if cfg.url != nil {
 			ctx, cancel := context.WithCancel(ctx)
-			p := httputil.NewSingleHostReverseProxy(cfg.url)
-			// ReverseProxy requiring explicitly set Hostname at both HttpRequest and HttpRequest.URL.
-			p.Director = func(req *http.Request) {
-				req.URL.Scheme = cfg.url.Scheme
-				req.Host = cfg.url.Hostname()
-				req.URL.Host = cfg.url.Hostname()
+			p := httputil.ReverseProxy{
+				Director: func(req *http.Request) {
+					req.URL.Scheme = cfg.url.Scheme
+					req.Host = cfg.url.Hostname()
+					req.URL.Host = cfg.url.Hostname()
+				},
 			}
 			p.Transport = &oauth2.Transport{
 				Source: ccc.TokenSource(ctx),
 			}
 
 			s := http.Server{
 				Addr:    cfg.server.listen,
-				Handler: p,
+				Handler: &p,
 			}
 			g.Add(func() error {
 				level.Info(logger).Log("msg", "starting proxy server", "address", s.Addr)