Horizontal pod autoscaling

Kubernetes can watch over your pods and scale them when the CPU utilization, memory, or some other metric crosses a threshold. The autoscaling resource specifies the details (the percentage of CPU and how often to check) and the corresponding autoscaling controller adjusts the number of replicas if needed.

The following diagram illustrates the different players and their relationships:

Figure 8.4: Horizontal pod autoscaling

As you can see, the horizontal pod autoscaler doesn’t create or destroy pods directly. It adjusts the number of replicas in a Deployment or StatefulSet resource and its corresponding controllers take care of actually creating and destroying pods. This is very smart because you don’t need to deal with situations where autoscaling conflicts with the normal operation of those controllers, unaware of the autoscaler efforts.

The autoscaler automatically does what we had to do ourselves before. Without the...