2. Create an application with the Admission Logic

The application could be created in any language. Go is the obvious choice since it's the language Kubernetes was built into.

App Logic consists of the following:

Webserver listening on a given port.
It receives an AdmissionReview request.
It unloads this payload and expects to find a Deployment
It exists if Deployment.Spec.Replicas are more than one
If sends an error message otherwise

Run the application:

go run . --cert certs/app.crt --key certs/app.key -logtostderr

It would show the following message:

I0325 22:25:24.278482  716010 main.go:53] Server running listening in port: 9000