HPAs used in the previous manner are an essential tool for ensuring that your clusters scale up as their workloads increase. The default behavior for HPA spreading in clusters ensure that maximum replicas are spread evenly first in all clusters. Let's say that you have 10 registered Kubernetes clusters in your federation control plane. If you have spec.maxReplicas = 30, each of the clusters will receive the following HPA spec:

spec.maxReplicas = 10

If you were to then set spec.minReplicas = 5, then some of the clusters will receive the following:

spec.minReplicas = 1

This is due to being unable to have a replica sum of 0. It's important to note that federation manipulates the minx/mix replicas it creates on the federated clusters, not by directly monitoring the target object metrics (in our case, CPU). The federated HPA controller is relying on HPAs within the federated cluster to monitor CPU utilization, which then makes changes to specs such as current and desired replicas.