ReplicaSets

As discussed earlier, having multiple replicas of our application ensures that it is still available even if a few replicas fail. This also makes it easy for us to scale our application to balance the load to serve more traffic. For example, if we are building a web application that's exposed to users, we'd want to have at least two replicas of the application in case one of them fails or dies unexpectedly. We would also want the failed replica to recover on its own. In addition to that, if our traffic starts growing, we would want to increase the number of Pods (replicas) running our application. A ReplicaSet is a Kubernetes controller that keeps a certain number of Pods running at any given time.

ReplicaSet acts as a supervisor for multiple Pods across the different nodes in a Kubernetes cluster. A ReplicaSet will terminate or start new Pods to match the configuration specified in the ReplicaSet template. For this reason, it is a good idea to use them even...