Ask HN: Recommendation for Rails/SSO forum

Hey guys, We're running a significant website built using Ruby On Rails and Warden for authentication. We'd like to setup a community forum to allow users provide each others tips. Ideally this forum would be multi language (not sure if it's essential) and we absolutely need that users don't need to reauthenticate through the forum. I tried Vanilla forums but it doesn't fit - their proxy-connect plugin is buggy and breaks from a version to another. Do you guys have any recommendations ? Thanks for your help !