The Kubernetes Scheduler

As mentioned in the introduction, a typical cluster has several nodes. When you create a Pod, Kubernetes has to choose a node and assign the Pod to it. This process is known as Pod scheduling.

The Kubernetes component that is responsible for deciding which node a Pod should be assigned to for execution is called a scheduler. Kubernetes comes with a default scheduler that suffices for most use cases. For example, the default Kubernetes Scheduler spreads the load evenly in the cluster.

Now, consider a scenario in which two different Pods are expected to communicate with each other very often. As a system architect, you may want them to be on the same node to reduce latency and free up some internal networking bandwidth. The Scheduler does not know the relationship between different types of Pods, but Kubernetes provides ways to inform the Scheduler about this relationship and influence the scheduling behavior so that these two different Pods can be hosted...