Custom Logstash docker image creation

Is there a guide that describes how to create your own Logstash image, especially for Kubernetes/Openshift?

I'm looking for something similar to this:

Why do you need to create your own image? Why can't you either extend the existing images or use the existing dockerfiles as a starting point?

I have to use company approved images, not permitted to do things like yum installs. We don't have access to public registries e.g. Docker Hub. We use our own internal ones.