public class DynamicFileProviderOptions
{
    public string CurrentSlot { get; set; }
}

public class DynamicFileProvider : IFileProvider
{
    private PhysicalFileProvider _physicalFileProvider;
    private const string DefaultSlotName = "Slot1";

    public DynamicFileProvider(IOptionsMonitor<DynamicFileProviderOptions> optionsMonitor, IWebHostEnvironment webHostEnvironment)
    {
        var webRoot = webHostEnvironment.ContentRootPath;
        _physicalFileProvider = new PhysicalFileProvider(Path.Combine(webRoot, optionsMonitor.CurrentValue.CurrentSlot ?? DefaultSlotName));
        optionsMonitor.OnChange(options =>
        {
            var path = Path.Combine(webRoot, options.CurrentSlot);
            _physicalFileProvider = new PhysicalFileProvider(path);
        });
    }

    public IDirectoryContents GetDirectoryContents(string subpath)
    {
        return _physicalFileProvider.GetDirectoryContents(subpath);
    }

    public IFileInfo GetFileInfo(string subpath)
    {
        return _physicalFileProvider.GetFileInfo(subpath);
    }

    public IChangeToken Watch(string filter)
    {
        return _physicalFileProvider.Watch(filter);
    }
}

var builder = Host.CreateDefaultBuilder(args);
builder.ConfigureWebHostDefaults(webHostBuilder =>
{
    webHostBuilder.ConfigureServices((context, services) =>
    {
        services.Configure<DynamicFileProviderOptions>(context.Configuration);
        services.AddSingleton<DynamicFileProvider>();
    });
    webHostBuilder.Configure(app =>
    {
        var dynamicFileProvider = app.ApplicationServices.GetRequiredService<DynamicFileProvider>();
        app.UseStaticFiles(new StaticFileOptions()
        {
            FileProvider = dynamicFileProvider,
        });
    });
});
var host = builder.Build();
host.Run();

app.Map(new PathString("/redeploy"), appBuilder => appBuilder.Run(context =>
{
    if (context.RequestServices.GetRequiredService<IConfiguration>() is ConfigurationRoot configuration)
    {
        var currentSlot = configuration["CurrentSlot"];
        configuration["CurrentSlot"] = "Slot2" != currentSlot ? "Slot2" : "Slot1";
        configuration.Reload();
        return context.Response.WriteAsync("Success");
    }
    return Task.CompletedTask;
}));