GitOps Cookbook

Chapter 5. Helm

In Chapter 4, you learned about Kustomize, a simple yet powerful tool to manage Kubernetes resources. But another popular tool aims to simplify the Kubernetes resources management too: Helm.

Helm works similarly to Kustomize, but it’s a template solution and acts more like a package manager, producing artifacts that are versionable, sharable, or deployable.

In this chapter, we’ll introduce Helm, a package manager for Kubernetes that helps install and manage Kubernetes applications using the Go template language in YAML files.

The first step is to create a Helm project and deploy it to a Kubernetes cluster (see Recipes 5.1 and 5.2). After the first deployment, the application is updated with a new container image, a new configuration value, or any other field, such as the replica number (see Recipe 5.3).

One of the differences between Kustomize and Helm is the concept of a Chart. A Chart is a packaged artifact that can be shared and contains multiple elements like dependencies on other Charts (see Recipes 5.4, 5.5, and 5.6).

Application configuration values are properties usually mapped as a Kubernetes ConfigMap. Any change (and its consequent update on the cluster) on a ConfigMap doesn’t trigger a rolling update of the application, which means that the application will run with the previous version until you manually restart it.

Helm provides some functions to automatically execute a rolling update when the ConfigMap of an application changes (see Recipe ...