Bringing an old thread to life again, sorry!
I'd also love some help with the instructions for running this in a Docker image. It would make life a bit easier for deploying this in DigitalOcean.
I wrote a tutorial about setting up single sign-on for NodeBB.
Full disclosure, I wrote it using my employers OAuth server (FusionAuth) as the user identity provider.
But the plugin and steps should work with any OAuth server. The plugin is here: https://github.com/FusionAuth/nodebb-plugin-fusionauth-oidc