OAuth2 Login force specific Authentication Provider / Skip Discovery Page

[bliszewski]

Greetings Canvas Developers,

We currently support 2 Authentication providers for our Canvas environment,

1. Our own SAML provider for registered students, faculty, and staff, and
2. Local Canvas logins for some extra-curricular and outreach programs.

So, we have set up a Discovery Page to help direct people to the appropriate login form. This all works well for general access.

But, we also have some specific integrations--like a mobile app which use OAuth2--that are only available to the registered students, faculty, and staff, and so having the Discovery Page in this flow is redundant and for many people undesirable.

Is there any way to direct an OAuth2 login to use a specific authentication provider and bypass the discovery page in these flows?

We've looked in the Developer Key settings and OAuth2 Endpoints, and haven't seen anything, but maybe I'm just not understanding some of these options?

Has anyone else done something similar and found a way around this?

[bliszewski]

To answer my own question here, there seems to be an (undocumented?) `authentication_provider` URL parameter that can be passed into a Canvas URL, including login/oauth2/auth, which will automatically direct the user to the indicated Authentication Provider.

[matthew_buckett]

Nice find, I think the underlying code that supports this is:

https://github.com/instructure/canvas-lms/blob/master/app/controllers/oauth2_provider_controller.rb#...