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Helm Introduction

Helm is package manager and a templating engine for Kubernetes. It allows you to define, install, and upgrade even the most complex Kubernetes applications. It's like apt, yum, or homebrew for Kubernetes. Primary use case is application deployment and environment management.

Helm Architecture

The new architecture of Helm 3 is very simple. It has only client-side components. The server-side components like Tiller are removed in Helm 3. Helm 3 is a client-side application that interacts with the Kubernetes API server.

Using a Helm Chart

To deploy an application using Helm, you need to create a Helm chart. A Helm chart is a collection of files that describe a related set of Kubernetes resources. A single chart might be used to deploy something simple, like a memcached pod, or something complex, like a full web app stack with HTTP servers, databases, caches, and so on.

First we need to add the repository to the helm

helm repo add bitnami https://charts.bitnami.com/bitnami
  • We can update the repository using the following command
helm repo update
  • Then we can install the chart using the following command
helm install postgres bitnami/postgresql

we can search for the available charts using the following command

helm search repo bitnami

Or search the available versions of the chart using the following command

helm search repo bitnami/postgresql --versions

We can also pull the chart locally to look at the configuration files. --version flag is used to specify the version of the chart not the app version

helm pull bitnami/postgresql --version 16.3.0

We can give values to the chart using the values flag and padding the values in the yaml file

helm install postgresql bitnami/postgresql --values values.yaml

The values.yaml file should look like this

commonAnnotations:
    foo: bar

We can upgrade the chart using the following command

helm upgrade --install postgresql bitnami/postgresql --values values.yaml --version=16.4.0 --namespace=my-namespace

We can rollback the chart using the following command postgresql is the release name we can get the release name using helm list.

helm rollback postgresql

To check helm release status

helm list

To check values provided by the user. Again postgresql is the release name

helm get values postgresql

We can also get actual manifest files that are generated by the helm chart. Again postgresql is the release name

helm get manifest postgresql

We can uninstall the chart using the following command. Again postgresql is the release name

helm uninstall postgresql

Creating our own Helm Chart

  • We can create our own helm chart using the following command. It will generate a dir with all the boilerplate code.
helm create mychart
  • We can install the chart using the following command. mychart is the chart name and ./mychart is the path to the chart
helm install mychart ./mychart

We can also apply with a values file

helm install mychart ./mychart --values values.yaml

Helm Hooks

Helm hooks are a way to interact with the lifecycle of a release. They allow you to intervene at certain points in a release's life cycle. Helm supports the following hooks:

  • pre-install - Runs before any templates are rendered.
  • post-install - Runs after all templates have been rendered and resources have been created.

What's next?

Learning Resources - Learn more about Helm with these resources.