Helm

Helm is a package manager for Kubernetes that helps you define, install, and upgrade Kubernetes applications. It uses a packaging format called charts, which contain all the necessary Kubernetes resource definitions to run an application. Helm simplifies the deployment and management of applications on Kubernetes clusters.

While Kustomize excels at declarative configuration management, Helm takes a different approach focused on templating and package management. Helm is particularly valuable when you need to:

• Share applications across teams and organizations
• Handle complex configurations with conditional logic
• Manage application lifecycles (install, upgrade, rollback)
• Leverage existing ecosystem of pre-built charts

Core Concepts

Charts

Helm uses a packaging format called charts. A 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.

A Helm package containing:

• Chart.yaml - metadata about the chart
• values.yaml - default configuration values
• templates/ - Kubernetes manifest templates
• Optional dependencies and documentation

Releases

A release is an instance of a chart running in a Kubernetes cluster. You can install the same chart multiple times with different configurations.

Values

Values are the configuration parameters that customize how a chart behaves when installed.

info

This lab focuses on using Helm charts rather than authoring them. For chart development, see the official guide.

Helm CLI

The helm CLI tool is typically used in conjunction with a Kubernetes cluster to manage the deployment and lifecycle of applications. It provides a consistent and repeatable way to package, install, and manage applications on Kubernetes, making it easier to automate and standardize application deployments across different environments.

The CLI is already installed in our IDE:

~$helm version

Installing a Helm chart

Let's install the UI component of our sample application using its Helm chart instead of Kustomize manifests. When you install a chart using the Helm package manager, it creates a new release for that chart. Each release is tracked by Helm and can be upgraded, rolled back, or uninstalled independently from other releases.

First let's delete the existing UI application:

~$kubectl delete namespace ui

Next we can install the chart:

~$helm install ui \

oci://public.ecr.aws/aws-containers/retail-store-sample-ui-chart \

--version 1.2.1 \

--create-namespace --namespace ui \

--wait

We can break this command down as follows:

• Use the install sub-command to instruct Helm to install a chart
• Name the release ui
• Use the chart hosted in ECR Public with a specific version
• Install the chart in the ui namespace
• Wait for Pods in the release to get to a ready state

Once the chart is installed we can list the releases in our EKS cluster:

~$helm list -A

NAME   NAMESPACE  REVISION  UPDATED                                  STATUS    CHART                               APP VERSION

ui     ui         1         2024-06-11 03:58:39.862100855 +0000 UTC  deployed  retail-store-sample-ui-chart-X.X.X

We can also see application running in the namespace we specified:

~$kubectl get pod -n ui

NAME                     READY   STATUS    RESTARTS   AGE

ui-55fbd7f494-zplwx      1/1     Running   0          119s

Configuring chart options

In the example above we installed the chart with its default configuration. Often you'll need to provide configuration values to charts during installation to modify the way the component behaves.

There are two common ways to provide values to charts during installation:

1. Create YAML files and pass them to Helm using the -f or --values flag
2. Pass values using the --set flag followed by key=value pairs

Let's combine these methods to update our UI release. We'll use this values.yaml file:

~/environment/eks-workshop/modules/introduction/basics/helm/values.yaml

podAnnotations:
  my-annotation: my-value

app:
  theme: orange

This adds several custom Kubernetes annotations to the Pods, as well as overriding the UI theme.

How do I know what values to use?

Although many Helm charts have relatively consistent values for configuring common aspects like replicas and Pod annotations, each Helm chart can have its own unique set of configuration. When installing and configuring any given chart you should review its available configuration values via its documentation.

We'll also add additional replicas using the --set flag:

~$helm upgrade ui \

oci://public.ecr.aws/aws-containers/retail-store-sample-ui-chart \

--version 1.2.1 \

--create-namespace --namespace ui \

--set replicaCount=3 \

--values ~/environment/eks-workshop/modules/introduction/basics/helm/values.yaml \

--wait

List the releases:

~$helm list -A

NAME   NAMESPACE  REVISION  UPDATED                                  STATUS    CHART                                APP VERSION

ui     ui         2         2024-06-11 04:13:53.862100855 +0000 UTC  deployed  retail-store-sample-ui-chart-X.X.X   X.X.X

You'll notice that the revision column has updated to 2 as Helm has applied our updated configuration as a distinct revision. This would allow us to rollback to our previous configuration if necessary.

You can view the revision history of a given release like this:

~$helm history ui -n ui

REVISION  UPDATED                   STATUS      CHART                               APP VERSION  DESCRIPTION

1         Tue Jun 11 03:58:39 2024  superseded  retail-store-sample-ui-chart-X.X.X  X.X.X        Install complete

2         Tue Jun 11 04:13:53 2024  deployed    retail-store-sample-ui-chart-X.X.X  X.X.X        Upgrade complete

To check that our changes have taken effect list the Pods in the ui namespace:

~$kubectl get pods -n ui

NAME                     READY   STATUS    RESTARTS   AGE

ui-55fbd7f494-4hz9b      1/1     Running   0          30s

ui-55fbd7f494-gkr2j      1/1     Running   0          30s

ui-55fbd7f494-zplwx      1/1     Running   0          5m

You can see we now have 3 replicas running. We can also verify our annotation was applied by inspecting the Deployment:

~$kubectl get -o yaml deployment ui -n ui | yq '.spec.template.metadata.annotations'

my-annotation: my-value

[...]

Removing releases

We can similarly uninstall a release using the CLI:

~$helm uninstall ui --namespace ui --wait

This will delete all the resources created by the chart for that release from our EKS cluster.

When to Use Helm

Helm is ideal when:

• You need complex templating and conditional logic
• You're distributing applications to multiple teams
• You want sophisticated release management
• You're leveraging existing charts from the ecosystem
• You need to support many different configuration scenarios

Key Takeaways

• Templating power: Helm's Go templates enable complex, conditional configurations
• Release management: Built-in support for upgrades, rollbacks, and release history
• Package ecosystem: Large repository of pre-built charts for common applications
• Values-driven: Configuration through structured values files and command-line overrides
• Lifecycle management: Complete application lifecycle from install to uninstall

Helm provides a powerful templating and package management solution for Kubernetes applications. It's particularly valuable when you need to distribute applications widely or handle complex configuration scenarios.

Both Helm and Kustomize have their place in the Kubernetes ecosystem, and many teams use both tools for different use cases. Understanding both approaches will help you choose the right tool for each situation.

Next, you can explore the Fundamentals module to dive deeper into EKS-specific concepts and advanced Kubernetes patterns.