How to authenticate user using GitHub app?

I setup a GitHub application for my organization and have authentication against GitHub for my webapp working via the instructions at https://developer.github.com/v3/guides/basics-of-authentication/.  I only want users that are a member of my github organization to have access to my web application.  How do I limit who can login via my GitHub app?

Thanks

Hi @mlbiam,

Thanks for being here! GitHub Apps are installed on a specific user or organization and the permissions scope of such an installation is that single user or organization.

If you want to see which repositories the installation can access on behalf of a user, then there’s a different endpoint for that:

https://developer.github.com/v3/apps/installations/#list-repositories-accessible-to-the-user-for-an-installation