As you already saw, Prometheus Adapter comes with a set of default rules that provide many metrics that we do not need, and not all those that we do. It's wasting CPU and memory by doing too much, but not enough. We'll explore how we can customize the adapter with our own rules. Our next goal is to make the adapter retrieve only the nginx_ingress_controller_requests metric since that's the only one we need. On top of that, it should provide that metric in two forms. First, it should retrieve the rate, grouped by the resource.
The second form should be the same as the first but divided with the number of replicas of the Deployment that hosts the Pods where Ingress forwards the resources.
That one should give us an average number of requests per replica and will be a good candidate for our first HPA definition...