Metrics not updated automatically

[atul161]

ctx, cancel := context.WithCancel(ctx)
defer cancel()

srv := &http.Server{
	Addr:    config.ServerHost + ":" + config.PromthesiusPort,
	Handler: promhttp.HandlerFor(promthesusConfig.Registry, promhttp.HandlerOpts{}),
}
//initializing metrics
promthesusConfig.ServerMetrics.InitializeMetrics(grpcServer)
grpc_prometheus.Register(grpcServer)
// graceful shutdown
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
go func() {
	for range c {
		// sig is a ^C, handle it
	}
	_, cancel := context.WithTimeout(ctx, 30*time.Second)
	defer cancel()
	logger.Log.Info("graceful shutting down promthesius Server")
	_ = srv.Shutdown(ctx)
}()

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when i open a port ..it already intiliased with the default metrics ...but when we hit new request on server ..then the details not updated automatically. After refreshing same problem happens