WindowsService.cs

public partial class SelfHostServiceBase : ServiceBase
{
    private IDisposable _webapp;

    public SelfHostServiceBase()
    {
        InitializeComponent();
    }

    protected override void OnStart(string[] args)
    {
        _webapp = WebApp.Start<Startup>("http://localhost:8080");
    }

    protected override void OnStop()
    {
        _webapp?.Dispose();
    }
}