The nodebb.rb script has this:
# adapter = NodeBB::Mongo # @client = adapter.new('mongodb://127.0.0.1:27017/nodebb')
So you’d uncomment those and put the appropriate URL to connect to your mongo there and comment out the redis connection stuff. You probably need to add gem mongo to your Gemfile and bundle install.
I doubt it. I imagine that whoever wrote the script ran it in a development environment. You can endeavor to enter the container and add whatever stuff is needed to run it there.