Custom route that match a single specific url - asp.net-mvc

Question

In my mvc app, I want to dynamically generate a specific url :
https://myapp.corp.com/.well-known/microsoft-identity-association.json
This endpoint should produce a small file based on values in the web.config file. So I created this controller :
public class HostingController : Controller
{
// GET: Hosting
[OutputCache(Duration = 100, VaryByParam = "none")]
public ActionResult MicrosoftIdentityAssociation() => Json(new
{
associatedApplications = new[]
{
new { applicationId = WebConfigurationManager.AppSettings.Get("ClientId") }
}
});
}
And I changed the routing configuration like this :
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
"Azure domain registration",
".well-known/microsoft-identity-association.json",
new { controller = "Hosting", action= "MicrosoftIdentityAssociation" }
);
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
I expect the url to produce json like :
{
"associatedApplications": [
{
"applicationId": "1562019d-44f7-4a9d-9833-64333f52181d"
}
]
}
But when I target the url, I got a 404 error.
What's wrong ? how to fix ?

Answer 1

You can use a route attribute:
[Route("~/.well-known/microsoft-identity-association.json")]
[OutputCache(Duration = 100, VaryByParam = "none")]
public ActionResult MicrosoftIdentityAssociation()
{
..... your code
}
It was tested in postman.

Answer 2

Asp.Net MVC can't create route that have extension. I had to edit my Web.config to plug the MVC framework on this very specific file.
Specifically :
<system.webServer>
<handlers>
<add name="Azure domain verifier"
path=".well-known/microsoft-identity-association.json"
verb="GET" type="System.Web.Handlers.TransferRequestHandler"
preCondition="integratedMode,runtimeVersionv4.0" responseBufferLimit="0"
/>
</handlers>
</system.webServer>
From this point, I was able to route to my custom controller action using either routeconfig.cs file or the [RouteAttribute]