-
Go to developers.facebook.com and create an app:
-
Click Add Platform, choose Website, and enter
http://forum.example.com
in the Site URL field. -
Click on Settings on the left. Enter
forum.example.com
in the App Domains field. -
Enter your email in the Contact Email field
-
Under the Advanced tab (at the top), make sure Client OAuth Login is enabled. Enter
http://forum.example.com/auth/facebook/callback
in the Valid OAuth redirect URIs field. -
Click the Save Changes button.
-
The App ID and App Secret go in the
facebook_app_id
andfacebook_app_secret
settings in the users section. -
Go to Status & Review and change “available to the general public” to Yes.
Source: https://meta.discourse.org/t/configuring-facebook-login-for-discourse/13394