Helm Chart¶

• Welcome to the Helm Chart hands-on lab! In this tutorial, you’ll learn the essentials of Helm (version 3), the package manager for Kubernetes.
• You’ll build, package, install, and manage applications using Helm charts, gaining practical experience with real Kubernetes resources.

What will you learn¶

• What Helm is and why is it useful
• Helm chart structure and key files
• Common Helm commands for managing releases
• How to create, pack, install, upgrade, and rollback a Helm chart
• Troubleshooting and best practices

Introduction¶

• Helm is the package manager for Kubernetes.
• It simplifies the deployment, management, and upgrade of applications on your Kubernetes cluster.
• Helm helps you manage Kubernetes applications by providing a way to define, install, and upgrade complex Kubernetes applications.

• When packing applications as Helm charts, you gain a standardized and reusable approach for deploying and managing your services.

• A Helm chart consists of a few files that define the Kubernetes resources that will be created when the chart is installed.

• These files include the:
  • Chart.yaml file, which contains metadata about the chart, such as its name and version, and the chart’s dependencies and maintainers.
  • values.yaml file, which contains the configuration values for the chart.
  • The templates directory which contains the Kubernetes resource templates to be used to create the actual resources in the cluster.

Terminology¶

• Chart

  • A Helm package is called a chart.
  • Charts are versioned, shareable packages that contain all the Kubernetes resources needed to run an application.

• Release

  • A specific instance of a chart is called a release.
  • Each release is a deployed version of a chart, with its own configuration, resources, and revision history.

• Repository

  • A collection of charts is stored in a Helm repository.
  • Helm charts can be hosted in public or private repositories for easy sharing and distribution.

Chart files and folders¶

codewizard-helm-demo Helm Chart tructure¶

- Chart.yaml        # Defines chart metadata and values schema
- values.yaml       # Default configuration values
- templates/        # Deployment templates using Go templating language
  - deployment.yaml # Deployment manifest template
  - service.yaml    # Service manifest template
- README.md         # Documentation for your chart 

Common Helm Commands¶

Here are some of the most common Helm commands you’ll use when working with Helm charts:

Lab¶

Step 01 - Installing Helm¶

• Before you can use the codewizard-helm-demo chart, you’ll need to install Helm on your local machine.

• Helm install methods by OS:

Verify Installation¶

• To confirm that Helm is installed correctly, run:

$ helm version

## Expected output
version.BuildInfo{Version:"xx", GitCommit:"xx", GitTreeState:"clean", GoVersion:"xx"}

Step 02 - Creating our Helm chart¶

• Creating our custom codewizard-helm-demo Helm chart

• The custom codewizard-helm-demo Helm chart is build upon the following K8S resources:

  • ConfigMap
  • Deployment
  • Service

• As mentioned above, we will also have the following Helm resources:

  • Chart.yaml
  • values.yaml
  • templates/_helpers.tpl

Create a New Chart¶

• First, we need to create a Helm chart using the helm create command.
• This command will generate the necessary file structure for your new chart.

helm create codewizard-helm-demo

Navigate to the Chart Directory¶

cd codewizard-helm-demo

Write the chart content¶

• Copy the content of the chart folder (in this lab) to the chart directory (overwriting the files).

Step 03 - Pack the chart¶

• After we have created or customized our chart, we need to pack it as .tgz file, which can then be shared or installed.

helm package¶

helm package codewizard-helm-demo

• This command will create a file called codewizard-helm-demo-<version>.tgz inside your current directory.

Step 04 - Validate the chart content¶

helm template¶

• Helm allows you to generate the Kubernetes manifests based on the templates and values files without actually installing the chart.
• This is useful to preview what the generated resources will look like:

helm template codewizard-helm-demo

## This will output the rendered Kubernetes manifests to your terminal

Step 05 - Install the chart¶

• Install the codewizard-helm-demo chart into Kubernetes cluster

The helm install command¶

• This command installs a chart archive.
• The install argument must be a chart reference, a path to a packed chart, a path to an unpacked chart directory or a URL.
• To override values in a chart, use:
  • --values - pass in a file
  • --set - pass configuration from the command line

# Install the packed helm chart
helm install codewizard-helm-demo codewizard-helm-demo-0.1.0.tgz

Step 06 - Verify the installation¶

• Examine newly created Helm chart release, and all cluster created resources:

# List the installed helms
helm ls

# Check the resources
kubectl get all -n codewizard

Step 07 - Test the service¶

• Perform an HTTP GET request, send it to the newly created cluster service.
• Confirm that the response contains the CodeWizard Helm Demo message passed from the values.yaml file.

kubectl run busybox         \
        --image=busybox     \
        --rm                \
        -it                 \
        --restart=Never     \
        -- /bin/sh -c "wget -qO- http://codewizard-helm-demo.codewizard.svc.cluster.local"

### Output: 
CodeWizard Helm Demo

Step 08 - Upgrade the release to newer version¶

• Perform a Helm upgrade on the codewizard-helm-demo release:

# upgrade and pass a different message than the one from the default values
# Use the --set to pass the desired value
helm  upgrade \
  codewizard-helm-demo \
  codewizard-helm-demo-0.1.0.tgz \
  --set nginx.conf.message="Helm Rocks"

Step 09 - Check the upgrade¶

• Perform another HTTP GET request.
• Confirm that the response now has the updated message Helm Rocks:

kubectl run busybox         \
        --image=busybox     \
        --rm                \
        -it                 \
        --restart=Never     \
        -- /bin/sh -c "wget -qO- http://codewizard-helm-demo.codewizard.svc.cluster.local"

### Output: 
Helm Rocks

Step 10 - History¶

• Examine the codewizard-helm-demo release history

helm history¶

• helm history prints historical revisions for a given release.
• A default maximum of 256 revisions will be returned.

$ helm history codewizard-helm-demo

### Sample output
REVISION        UPDATED    STATUS          CHART                           APP VERSION     DESCRIPTION     
1               ...        superseded      codewizard-helm-demo-0.1.0      1.19.7          Install complete
2               ...        deployed        codewizard-helm-demo-0.1.0      1.19.7          Upgrade complete

Step 11 - Rollback¶

helm rollback¶

• Rollback the codewizard-helm-demo release to previous version:

$ helm rollback codewizard-helm-demo

### Output:
Rollback was a success! Happy Helming!

• Check again to verify that you get the original message!

Finalize & Cleanup¶

• To remove all resources created by this lab, uninstall the codewizard-helm-demo release:

helm uninstall codewizard-helm-demo

• (Optional) If you have created a dedicated namespace for this lab, you can delete it by runniung:

kubectl delete namespace codewizard

Troubleshooting¶

• Helm not found:

Make sure Helm is installed and available in your PATH. Run the following to verify:

helm version

• Pods not starting:

Check pod status and logs by running the following commands:

kubectl get pods -n codewizard
kubectl describe pod <pod-name> -n codewizard
kubectl logs <pod-name> -n codewizard

• Service not reachable:

Ensure the service and pods are running by running the following commands:

kubectl get svc -n codewizard
kubectl get pods -n codewizard

• Values not updated after upgrade:

Double-check your --set or --values flags and confirm the upgrade by running:

helm get values codewizard-helm-demo

Next Steps¶

• Try creating your own Helm chart for a different application.
• Explore Helm chart repositories like Artifact Hub.
• Learn about advanced Helm features, such as: dependencies, hooks, and chart testing.
• Integrate Helm with CI/CD pipelines for automated deployments.
• Read more in the official Helm documentation.