Stateful versus stateless applications in Kubernetes

A stateless Kubernetes application is an application that doesn't manage its state in the Kubernetes cluster. All of the state is stored outside the cluster and the cluster containers access it in some manner. In this section, we'll understand why state management is critical to the design of a distributed system and the benefits of managing state within the Kubernetes cluster.

Understanding the nature of distributed data-intensive apps

Let's start from the basics here. Distributed applications are a collection of processes that run on multiple machines, process inputs, manipulate data, expose APIs, and possibly have other side effects. Each process is a combination of its program, its runtime environment, and its inputs and outputs. The programs you write at school get their input as command-line arguments, maybe they read a file or access a database, and then write their results to the screen or a file or a database. Some programs keep...