Website "Down for maintenance" best practice

Question

I have a public facing website (Banking related) which is due for a PROD update in the next coming weeks. I need to display a "Down for maintenance" page during the outage window.Because the bank has provided me with specific requirements for the page, which needs to be styled exactly the same as the website itself, I dont think the app_offline.htm solution will work for me as I wont be able to access my style sheets and images, because IIS redirect all requests to this page.

I was wondering, what would be the best solution design so I can make use of the styling and images in my website on my maintenance page? I was told that a good way to do this is to create a new website, include the styling and images, and deploy that as a seperate website in IIS< and then during the outage window I switch the IP address binding in IIS to point to my maintenance site. Once maintenance is complete, I switch it back to point to the main website. Is this a good way to go about it?

UPDATE:

I implemented the following, and it seems to work pretty well. When I drop the Outage.htm or Maintenance.htm file into my web root folder, it will redirect accordingly. Outage and scheduled maintenance has different styling and content so I had to create 2 pages. Also, when in outage or maintenance mode, and request is coming from localhost, then dont redirect, to allow for testing website after doing maintenance while blocking external requests.

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new CheckForDownPage());
    }
}

   public sealed class CheckForDownPage : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        string ipAddress = HttpContext.Current.Request.UserHostAddress;

        var outagePage = System.Web.Hosting.HostingEnvironment.MapPath("~/Outage.htm");
        var maintenancePage = System.Web.Hosting.HostingEnvironment.MapPath("~/Maintenance.htm");

        var isOutage = System.IO.File.Exists(outagePage);
        var isMaintenance = System.IO.File.Exists(maintenancePage);            

        if ( (isOutage || isMaintenance) && ipAddress != "::1")
        {
            filterContext.HttpContext.Response.Clear();                
            filterContext.HttpContext.Response.StatusCode = (int)HttpStatusCode.ServiceUnavailable;
            filterContext.HttpContext.Response.StatusDescription = "Service Unavailable.";

            filterContext.HttpContext.Response.WriteFile(isOutage ? outagePage : maintenancePage);

            filterContext.HttpContext.Response.End();
            return;
        }

        base.OnActionExecuting(filterContext);
    }
}

Answer 1

I implemented the following, and it seems to work pretty well. When I drop the Outage.htm or Maintenance.htm file into my web root folder, it will redirect accordingly. Outage and scheduled maintenance has different styling and content so I had to create 2 pages. Also, when in outage or maintenance mode, and request is coming from localhost, then dont redirect, to allow for testing website after doing maintenance while blocking external requests.

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new CheckForDownPage());
    }
}

   public sealed class CheckForDownPage : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        string ipAddress = HttpContext.Current.Request.UserHostAddress;

        var outagePage = System.Web.Hosting.HostingEnvironment.MapPath("~/Outage.htm");
        var maintenancePage = System.Web.Hosting.HostingEnvironment.MapPath("~/Maintenance.htm");

        var isOutage = System.IO.File.Exists(outagePage);
        var isMaintenance = System.IO.File.Exists(maintenancePage);            

        if ( (isOutage || isMaintenance) && ipAddress != "::1")
        {
            filterContext.HttpContext.Response.Clear();                
            filterContext.HttpContext.Response.StatusCode = (int)HttpStatusCode.ServiceUnavailable;
            filterContext.HttpContext.Response.StatusDescription = "Service Unavailable.";

            filterContext.HttpContext.Response.WriteFile(isOutage ? outagePage : maintenancePage);

            filterContext.HttpContext.Response.End();
            return;
        }

        base.OnActionExecuting(filterContext);
    }
}