Helm: Dry Run and Template Debug

Helm, the Kubernetes package manager, has become an indispensable tool for managing complex applications deployed on Kubernetes clusters. As Helm charts grow in complexity, ensuring smooth deployments becomes crucial. In this article, we will delve into two powerful Helm features that aid in troubleshooting and debugging: 'Dry Run' and 'Template Debug.' These features allow users to simulate deployments and inspect rendered templates before applying changes to the cluster, ensuring a more predictable and error-free release process.

Dry Run: Simulating Deployments

Helm's 'Dry Run' feature is a lifesaver when you want to preview changes without actually applying them to your Kubernetes cluster. It's like a rehearsal before the actual performance. To perform a dry run, use the following Helm command:

helm install --dry-run --debug <release-name> <chart>

• --dry-run: Indicates that the operation should be simulated.
• --debug: Prints out the rendered templates to the console for inspection.

Step-by-Step Instructions:

1. Open your terminal and navigate to the directory containing your Helm chart.

2. Run the helm install command with the --dry-run and --debug flags, specifying the release name and chart.

helm install --dry-run --debug my-release ./my-chart

3. Examine the output to ensure that the rendered templates match your expectations.

4. No changes are made to the cluster during a dry run. If everything looks good, proceed with the actual deployment.

Template Debug: Inspecting Rendered Templates

The 'Template Debug' feature allows you to inspect the rendered Kubernetes manifests before applying them. This is particularly useful for troubleshooting issues related to chart templates. To enable template debugging, use the following command:

helm install --debug <release-name> <chart> --set debug=true

• --debug: Enables debug mode, printing out additional information.
• --set debug=true: Sets the debug flag in the chart values.

More Examples:

1. Run the following command to enable template debugging:

helm install --debug my-release ./my-chart --set debug=true

2. Review the output to gain insights into the rendered templates and troubleshoot any issues.

3. Once you've identified and resolved any problems, proceed with the actual deployment without the debug flag.

In the complex world of Kubernetes deployments, Helm's 'Dry Run' and 'Template Debug' features provide a safety net, allowing operators and developers to catch issues before they impact the cluster. By simulating deployments and inspecting templates, you gain confidence in the changes you're about to make. Incorporating these practices into your Helm workflow will undoubtedly contribute to smoother, more reliable releases.