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Learn how to effectively read file content in Helm helper charts for sharing common configurations across your applications.
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How to Read File in Helm Helper Charts: A Comprehensive Guide

When working with Helm, a package manager for Kubernetes, you might find yourself needing to share common configurations across multiple applications. This is especially true for configurations like logging.xml, which are often reused in different app charts. In this guide, we will discuss how to create a helper chart to efficiently manage and serve file content to other charts.

The Problem: Sharing Configurations with Helm

Imagine you have multiple applications that all require a consistent logging configuration. Instead of duplicating the logback.xml files in each application’s chart, you want to centralize this configuration. This will not only save time but also simplify updates and maintenance.

You might think to create a template in a helper chart to read the configuration file. However, you might face challenges, such as the template not being able to access the resource files in the helper chart when used in the main chart.

The Initial Attempt

In your initial setup, you likely attempted to define a helper template as follows:

[[See Video to Reveal this Text or Code Snippet]]

And your file structure looked like this:

[[See Video to Reveal this Text or Code Snippet]]

However, when implementing this in your main chart, you found it only worked if you had the resources/logging.xml file in the app chart itself.

The Solution: Implementing a Centralized Template

After some exploration, you will find a better solution that allows for dynamic templates to share configurations effectively. Instead of sourcing from a resource file directly, you will create an additional helper template as follows:

[[See Video to Reveal this Text or Code Snippet]]

Updated ConfigMap in the Main Chart

In your main chart, the configuration for the ConfigMap should now look like this:

[[See Video to Reveal this Text or Code Snippet]]

This approach effectively allows the usage of a dynamic template that includes both the default logging configuration and any custom configurations you need to apply.

Benefits of This Approach

Centralized Configuration: Allows you to maintain logging configurations in a single location.

Ease of Maintenance: Updates to the logging configuration are required only in one place.

Flexibility: You can easily include custom configurations as needed.

Conclusion: Streamlining Your Helm Charts

In this guide, we walked through the process of sharing common configurations among different Helm charts effectively. By creating useful helper templates, you can enhance reusability and make your Helm charts cleaner and more maintainable.

If you're using Helm for Kubernetes deployments and have similar requirements, consider implementing this strategy for better configuration management. Happy charting!