Kubernetes Operators

Chapter 5. Sample Application: Visitors Site

Real, production-level applications are difficult. Container-based architectures are often made up of multiple services, each requiring their own configuration and installation process. Maintaining these types of applications, including the individual components and their interactions, is a time-consuming and error-prone process. Operators are designed to reduce the difficulty in this process.

A simple, one–container “Hello World” application isn’t going to provide enough complexity to fully demonstrate what Operators can do. To really help you understand the capabilities of Operators, we need an application that requires multiple Kubernetes resources with configuration values that cross between them to use for demonstration.

In this chapter we introduce the Visitors Site application, which we will use as an example in the following chapters that cover writing Operators. We’ll take a look at the application architecture and how to run the site, as well as the process of installing it through traditional Kubernetes manifests. In the chapters that follow, we’ll create Operators to deploy this application using each of the approaches provided by the Operator SDK (Helm, Ansible, and Go), and explore the benefits and drawbacks of each.

Application Overview

The Visitors Site tracks information about each request to its home page. Each time the page is refreshed, an entry is stored with details about the client, backend server, and timestamp. ...