Chapter 12: StatefulSet – Deploying Stateful Applications

In the previous chapter, we explained how you can use a Kubernetes cluster to run stateless workloads and applications and how to use Deployment objects for this purpose. Running stateless workloads in the cloud is generally easier to handle, as any container replica can handle the request without taking any dependencies on the results of previous operations by the end user. In other words, every container replica would handle the request in an identical way; all you need to care about is proper load balancing.

However, stateless workloads are only the easier part of running cloud applications. The main complexity is in managing the state of applications. By state, we mean any stored data that the application or component needs to serve the requests and it can be modified by these requests. The most common example of a stateful component in applications is a database – for example, it can be a relational MySQL...