Top 50 Helm Interview Question and Answers

11 Oct 2024 - Shyam Mohan

1. What is Helm?

   • Answer: Helm is a package manager for Kubernetes, which helps to manage Kubernetes applications in a standardized and efficient way.

2. Why use Helm in Kubernetes?

   • Answer: Helm simplifies Kubernetes deployments by managing charts, which are packages of pre-configured Kubernetes resources, making deployment and management of applications more predictable and repeatable.

3. What is a Helm Chart?

   • Answer: A Helm Chart is a collection of files describing a set of Kubernetes resources. It’s essentially a package of pre-configured Kubernetes objects.

4. What are the main components of a Helm Chart?

   • Answer: The main components are Chart.yaml, values.yaml, templates/, and README.md.

5. Explain the purpose of the values.yaml file in Helm.

   • Answer: The values.yaml file provides default configuration values for the chart, which can be overridden when the chart is installed.

6. What is Helm Tiller, and is it still used?

   • Answer: Tiller was the server-side component of Helm in Helm v2, but it was removed in Helm v3 for security and simplicity reasons.

7. What is a release in Helm?

   • Answer: A release is an instance of a chart running in a Kubernetes cluster.

8. How can you search for charts in Helm?

   • Answer: You can search for charts using the command helm search repo <keyword>.

9. What is a repository in Helm?

   • Answer: A repository is a place where charts are stored and shared, similar to package repositories for other package managers.

10. How do you add a repository in Helm?

    • Answer: You can add a repository using helm repo add <repo-name> <repo-url>.

11. How do you install a Helm Chart?

    • Answer: Using helm install <release-name> <chart-name>.

12. How do you upgrade a release in Helm?

    • Answer: Use helm upgrade <release-name> <chart-name>.

13. What is a Helm hook?

    • Answer: Hooks allow you to trigger actions at certain points in the release lifecycle, such as pre-install or post-delete.

14. How do you delete a release in Helm?

    • Answer: Using helm uninstall <release-name>.

15. Explain Helm Rollback.

    • Answer: helm rollback <release-name> <revision> reverts the release to a previous revision.

16. What is helm dependency update used for?

    • Answer: It updates chart dependencies based on the requirements listed in Chart.yaml.

17. How can you dry-run a Helm deployment?

    • Answer: Use helm install --dry-run --debug <release-name> <chart-name> to simulate a release.

18. How do you manage secrets in Helm?

    • Answer: Helm itself doesn’t manage secrets but you can use tools like Sealed Secrets or Helm Secrets for secure management.

19. What is the purpose of the helm lint command?

    • Answer: It is used to check a chart for syntax errors and best practices.

20. How can you override values in values.yaml?

    • Answer: Use --set in the command line or provide a custom values file with -f.

21. What is a Helm Plugin?

    • Answer: A Helm Plugin is an extension that adds custom features or functionalities to Helm.

22. Explain the helm package command.

    • Answer: It packages a chart directory into a chart archive file.

23. How does Helm handle dependencies?

    • Answer: Dependencies are listed in Chart.yaml and managed with helm dependency update to ensure required charts are installed.

24. What is a subchart in Helm?

    • Answer: A subchart is a chart that is used as a dependency within another chart.

25. Explain the use of helm template.

    • Answer: helm template renders the template files to standard output without actually deploying them.

26. What are common Helm Chart conventions?

    • Answer: Naming conventions, directory structure, template structure, and standard values.yaml parameters.

27. How would you debug a Helm chart?

    • Answer: Use helm install --dry-run --debug, check logs, and verify values.yaml configurations.

28. How can Helm Charts be versioned?

    • Answer: Charts are versioned in Chart.yaml using Semantic Versioning.

29. What are Helm Chart repositories like Artifact Hub?

    • Answer: Artifact Hub is a centralized repository for discovering Helm charts, Open Policy Agent, and other Kubernetes resources.

30. How do you migrate from Helm v2 to Helm v3?

    • Answer: Helm provides a plugin helm 2to3 that facilitates the migration process by removing Tiller and updating configurations.

31. What is the difference between helm install and helm upgrade --install?

    • Answer: helm install is used to create a new release, while helm upgrade --install performs an upgrade or installs if the release doesn’t exist.

32. How can you define environment-specific values in Helm?

    • Answer: Create different values files (e.g., values-prod.yaml) and use -f to apply them as needed.

33. Explain the helm env command.

    • Answer: It displays Helm’s environment variables.

34. What is the purpose of .Release.Name in Helm templates?

    • Answer: It refers to the release name of the current Helm deployment in templates.

35. How does Helm handle immutability with ConfigMaps?

    • Answer: By using a different name with each change or adding suffixes to make new immutable ConfigMaps.

36. Can you perform a rollback to a specific revision?

    • Answer: Yes, by using helm rollback <release-name> <revision>.

37. Explain helm repo update.

    • Answer: It refreshes the Helm repository cache to ensure the latest version of charts.

38. How do Helm tests work?

    • Answer: Helm tests allow for running custom tests (like readiness checks) post-installation to verify deployments.

39. What is .helmignore?

    • Answer: Similar to .gitignore, it specifies files to ignore when packaging Helm charts.

40. What is helm registry login?

    • Answer: Used for authenticating with an OCI registry before pulling/pushing Helm charts.

41. How do you troubleshoot failed Helm installs?

    • Answer: Use --debug, check Kubernetes logs, review template output, and check events in kubectl.

42. What is Helm’s default storage backend?

    • Answer: Helm stores release data in Kubernetes ConfigMaps or Secrets by default.

43. How would you use Helm in CI/CD pipelines?

    • Answer: By automating helm install, helm upgrade, and helm lint in the pipeline to ensure consistent deployments.

44. Explain Helm rollback best practices.

    • Answer: Always dry-run first, have version control for values.yaml, and use helm rollback cautiously.

45. How do you secure Helm deployments?

    • Answer: Restrict access to the Kubernetes API, use RBAC policies, and encrypt sensitive data.

46. Can Helm be used with GitOps workflows?

    • Answer: Yes, tools like ArgoCD and FluxCD support GitOps with Helm charts.

47. How does Helm manage upgrades with StatefulSets?

    • Answer: Helm doesn’t automatically roll StatefulSets due to immutability; StatefulSets often require a forced restart.

48. How do you deploy a specific Helm Chart version?

    • Answer: Use --version with helm install to specify the chart version.

49. What is the purpose of .Capabilities in Helm?

    • Answer: .Capabilities is a built-in object in Helm templates that provides information about Kubernetes capabilities.

50. Describe a Helm lifecycle hook example in real use.

    • Answer: A pre-install hook could be used to create a database or other dependencies before the main application is installed.