srv := &http.Server{Addr: ":8080", Handler: mux}

go func() {
    if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
        log.Printf("server error: %v", err)
    }
}()

ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
defer stop()
<-ctx.Done()

shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
_ = srv.Shutdown(shutdownCtx)