Use a Ngnix load balancer on a VSI to access an application on OpenShift in VPC

This blog post is a (bigger) cheat sheet about: - How to setup a simple Ngnix as a load balancer on a Virtual Server Instance (VSI) that runs in a Virtual Private Cloud (VPC)? - How to configure a Red Hat OpenShift project, to allow a REST endpoint invocation of an application inside the OpenShift project from a VSI instance that runs in the same VPC as the Red Hat OpenShift cluster?