We are about to deploy Prometheus (https://prometheus.io/) for the first time (in this book). We won't go into details behind the application except to say that it's fantastic and that you should consider it for your monitoring and alerting needs. At the risk of disappointing you, I will have to say that Prometheus is not in the scope of this chapter, and probably not even the book. We're using it only to demonstrate a few Kubernetes concepts. We're not trying to learn how to operate it.
Let's take a look the application's definition:
cat volume/prometheus.yml
The output is as follows:
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: Prometheus annotations: ingress.kubernetes.io/ssl-redirect: ...