Discourse is a conversation-oriented forum engine
Discourse supports its own Single-Sign-On scheme but is also compatible with standard protocols such as SAML and OpenID Connect, through plugins.
This documentation illustrates the OpenID Connect plugin.
Discourse can use the following OpenID Connect attributes to fill the user's profile:
Make sure you create a username and password for the Relying Party, and that the discourse callback URL is allowed : https://discourse.example.com/auth/oidc/callback
Install the Discourse OpenID Connect Plugin according to these instructions
Browse to your Discourse admin interface, and to the plugin settings