Have you checked out the demo app? The dockerfile is looking for a file ./nginx/env.conf
Here’s what that folder looks like in the demo app: https://github.com/jbielick/rails-kube-demo/tree/master/nginx
If you want nginx configured the way it’s described in this tutorial, you’ll need that file there so it can be copied into the docker container running the web workers (phusion passenger).
That should do it!