The recommended method of sharing sessions between two separate and distinct applications is through OAuth2. We recommend this approach because NodeBB maintains its own user records, so that we can keep track of user-related metrics and other data. Relying on another database would be tricky, prone to breaking, and quite possibly dangerous.
Luckily, it's quite straightforward to get things working with OAuth2!
The first step is getting your application to expose an OAuth2 endpoint. If you're running a Node.js based app, you can use a module called OAuth2orize.
When re-run ./nodebb setup, it did ask for the admin user/password (before it was an existing db present) so it's working now, thank you! In case someone would miss that or forget the admin pwd, what's the solution (via redis)? I saw a post somewhere but can't find it any more.