Empty/white page: /login/oauth2/confirm

[tomaas]

Hi. After requesting
https://my-testing-env.instructure.com/login/oauth2/auth?client_id=some-number&response_type=code&sc...
I get redirected to
https://my-testing-env.instructure.com/login/oauth2/confirm, but this
page is blank.

What is it, that I'm missing?

Thanks

[bbennett2]

Is this for a custom application? Normally in the OAuth flow, you would be redirected to some confirmation page created by the developer. 

Have you checked the console for errors? Or even the network tab for ay HTTP errors?

[tomaas]

You mention: some confirmation page created by the developer. Following the api docs about this endpoint https://canvas.instructure.com/doc/api/file.oauth_endpoints.html#get-login-oauth2-auth I understand that it is canvas itself that asks for user authentication and once granted by the user explicitly (in canvas ui), canvas then redirects/calls the redirect_uri paramater value that was passed to login/oauth2/auth.
If this is not the case, can you point to any resource about creating those confirmation views?

Thanks

[bbennett2]

You have to pass it an URL, but that URL doesn't have to have content on it. It's just somewhere to send the user once that code has been authenticated and the access token generated for the user. 

Are you developing this yourself? More specifics might help.

[tomaas]

Yes, i'm developing it myself. This is LTI 1.1 app, that needs to use a few rest api functions. I do pass it the url as you can see in my first post: redirect_uri=https://my-server.ngrok.io/canvas/authResp. However, canvas never calls this endpoint as the confirmation page is blank, I cannot click anywhere to grant permissions therefore canvas does not call my redirect_url.

However, if I mess intentionally the scope query paramater that I'm passing to login/oauth2/auth, then my redirect_uri=https://my-server.ngrok.io/canvas/authResp endpoint does get called reporting an error=invalid_scope.

[bbennett2]

So you're not even seeing the Canvas access page where you grant permissions to the application? I'm just trying to figure out where the break in the flow happens.

[tomaas]

Correct. I don't see the Canvas access page where I should grant permissions to the application. If I'm already logged in through other tab in canvas, I get the blank html page directly instead of access page for granting permissions. If I am not logged in, then I do get the login html first, but then once logged in, - blank html again. 

And no http errors btw in network tab.

[bbennett2]

OAuth was my sticking point while building an app for our teachers, so I know how frustrating it can be.

I can't move discussions, but it may be helpful to have one of the admins move this to the Developer's Group so more eyes see it.

I don't know it'd be helpful, but my app's code is open sourced on GitHub. Here's the auth flow and it may give some clues. What are you writing this in?

[bbennett2]

To add some intrigue to the thread, I was working with teachers today and got the white screen after authorizing when launching through Canvas. But, we were still able to launch at the application URL directly, which is strange.

My console showed a 500 error when trying to launch from Canvas, so something happened internally. I need to dig in deeper tomorrow.