When diving into the world of Kubernetes, one tool that often comes up is Helm. Helm is the package manager for Kubernetes, making it easier to define, install, and upgrade even the most complex Kubernetes applications. Whether you’re a hiring manager, a job aspirant, or just a curious tech aficionado, understanding Helm is crucial.

To assist, we've compiled a list of the most frequently asked Helm interview questions. This guide will not only prepare you for your next interview but will also provide a deeper understanding of Helm's pivotal role in the Kubernetes ecosystem.

1. What is Helm, and why is it important in the Kubernetes ecosystem?

Helm simplifies the deployment and management of applications on Kubernetes. It uses charts, which are packaged versions of Kubernetes applications, to deploy applications consistently across different environments.

2. Explain the difference between a Helm chart and a Helm release.

A Helm chart is a collection of files that describe a Kubernetes application. A Helm release is an instance of a chart that has been deployed to a Kubernetes cluster.

3. Describe Helm's architecture.

Helm has a client-server architecture. The client is helm, and the server component is tiller (used in Helm 2). In Helm 3, the Tiller component was removed, making Helm more secure and easier to use.

4. Why was Tiller removed in Helm 3?

Tiller posed security concerns as it required broad cluster-wide permissions. Helm 3 eliminated Tiller, allowing Helm to integrate directly with the Kubernetes API server, simplifying operations and boosting security.

5. What are Helm repositories, and why are they important?

Helm repositories are storage locations where Helm charts can be shared and published. They allow developers to share and reuse charts, leading to standardized and simplified deployments.

6. How can you update a Helm chart?

Use the helm upgrade command followed by the release name and the name/path of the chart.

7. Describe the difference between helm fetch and helm pull.

Both commands download charts, but helm fetch was used in Helm 2, while helm pull is the Helm 3 equivalent.

8. How do you roll back a release in Helm?

You can use the helm rollback command followed by the release name and the revision number to revert to a previous version of a release.

9. What is a Helm template?

Helm templates are files that define the Kubernetes resources of a chart. They support dynamic content using Go template language, enabling customization per deployment.

10. Can you explain Helm hooks?

Helm hooks allow you to define actions that should run at specific points in a release’s lifecycle, such as pre-install or post-upgrade.

11. What is the significance of values.yaml in Helm?

values.yaml is a default configuration file in a Helm chart. It allows users to customize the behavior of the chart without altering the actual templates. Parameters specified in values.yaml are overridden during chart installation or upgrade using the --set flag or by providing a custom values file.

12. How can you secure sensitive data, like passwords, in a Helm chart?

Sensitive data can be secured in Helm by using Kubernetes Secrets. Instead of embedding secrets directly in the values.yaml file, you can reference a Kubernetes Secret within the chart. Another practice is to use Helm's --set-string along with --set to pass sensitive data during runtime, ensuring they don't get stored in version control systems.

13. How can you list all the installed Helm releases in a namespace?

You can use the helm list or helm ls command. By default, it shows releases in the default namespace. To list releases in a specific namespace, you can use the -n or --namespace flag followed by the namespace name.

14. What is the difference between helm uninstall and helm delete?

Both commands are used to remove a Helm release, but their usage is version-specific. helm delete was the command used in Helm 2, whereas helm uninstall is used in Helm 3.

15. Can you explain the concept of Helm dependencies?

Helm dependencies are charts that a Helm chart relies on. The requirements.yaml (in Helm 2) or Chart.yaml (in Helm 3) file defines these dependencies. Dependencies ensure that when a chart is installed, all of its dependencies are retrieved and installed as well. You can manage dependencies using the helm dependency update command.

Conclusion:

Helm has emerged as a fundamental tool in the Kubernetes ecosystem, streamlining the deployment and management of applications. Whether you're looking to hire, be hired, or just learn, a strong understanding of Helm will undoubtedly be beneficial. Hopefully, this guide has shed light on some of the most pivotal aspects of Helm and prepared you for your next discussion or interview about it.