IdentityServer4 PostLogoutRedirectUri

Question

I am confused about how this is used.

Most examples I've seen have it given as "/signout-callback-oidc". That seems to indicate that it uses OIDC middleware in the process. What if I want to return to a specific client page?

The automatic redirect isn't working when I set IdentityServer's AccountOptions.cs property of AutomaticRedirectAfterSignOut to true. Further, during logout, I do not receive the client's PostLogoutRedirectUri.

So, is that link supposed to go to the OIDC middleware, or is it available for use to redirect to the client?

Answer 1

Your client has to be configured to request the callback to one of those URIs as part of the client-initiated sign-out flow.

IS4 clients can be configured with lists of allowable redirect URIs for both sign-in and sign-out, which I'm guessing is where you see /signout-callback-oidc -- if I remember right, either the docs or maybe the Quickstart code uses that, but there's nothing special about that particular URI name. (It isn't some OIDC standard, or a "well-known" name, or anything of that nature, as far as I know.)

The missing piece of the puzzle is to configure OIDC in the client application. You didn't mention what kind of application is on the client side, but in ASP.NET Core it's an option named SignedOutCallbackPath on the AddOpenIdConnect service:

services.AddOpenIdConnect("oidc", options =>
{
    options.SignInScheme = "Cookies";
    options.Authority = appConfig["OidcAuthority"];
    options.ClientId = appConfig["OidcClientId"];
    options.ClientSecret = appConfig["OidcClientSecret"];
    // etc

    options.SignedOutCallbackPath = "/jake-says-goodbye";
});

This causes the OIDC implementation to add a property to the sign-out request identifying that redirect URI. As long as your application properly identifies itself, as briefly mentioned in the docs here, and as long as /jake-says-goodbye is one of the approved post-logout redirect URIs on the IS4 side, you should get the callback you're expecting.

(I specifically mention "proper" identification because, based on github questions I've seen, it sounds like it might be more difficult to manage for a JS-based SPA client app versus whatever helpful things MVC does behind the scenes to manage server-to-server OIDC interaction. I can't speak to that as I've not had a need to implement any SPA clients with IS4 yet.)