title: How to change default callback of the Microsoft authentication provider login?
body: <p>In my ASP.Net Core app, I have implemented Microsoft External Login. I now wish to override the default login callback, which is listed by documentation to be <code>https://localhost:5001/signin-microsoft</code>, if of course running on localhost and on that port. The instructions on <a href="https://docs.microsoft.com/en-us/azure/app-service/configure-authentication-provider-microsoft" rel="nofollow noreferrer">here</a> then state that the callback override would be something like this: <code>https://contoso.azurewebsites.net/.auth/login/microsoftaccount/callback</code>. </p>
  
  <p>I am a bit confused on where the callback is meant to be implemented. At the moment I have <code>ExternalLoginCallback()</code> callback method implemented in a base Controller class. But from looking at the above example, it doesn't look like it should be part of a controller. </p>
  
  <p>Should the callback be inside <code>Startup.cs</code>, a Controller, or some other file I am not currently aware of?</p>