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In this lesson, you will learn how to use Kustomize transformers to modify Kubernetes configurations. Kustomize supports several built-in transformers, and you can also create custom ones. Here, we focus on a subgroup known as Common Transformers. Imagine you have multiple YAML files such as deployment.yaml and service.yaml. You might want to apply a common configuration—for example, adding a label like “org: KodeKloud” or appending “-dev” to resource names—across all these files. Manually updating each file in a production environment isn’t scalable or efficient. Kustomize transformers offer a systematic way to make consistent changes across all resources. Below are the original Kubernetes resource examples:
After applying Kustomize transformations, the resources might look like this:
Kustomize transformers are essential for ensuring that your Kubernetes configurations remain consistent and manageable across various environments.

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Common Transformation Methods

Below is an overview of common transformations available in Kustomize for managing Kubernetes resources:

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1. Common Label Transformation

This transformer automatically adds the specified labels to all Kubernetes resources. You can define the labels in your kustomization.yaml file as shown below:
For example, a transformed Service resource would appear as:

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2. Namespace Transformation

The namespace transformer assigns all Kubernetes resources to a specified namespace. By specifying the namespace in your kustomization.yaml, all resources will be modified accordingly. For example:
After this transformation, a Service resource might look like:
When applying namespace transformations, ensure that the specified namespace exists in your cluster to avoid deployment issues.

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3. Name Prefix and Suffix Transformation

This transformer enables you to systematically add a prefix or suffix to resource names. For instance, to prepend “KodeKloud-” and append “-dev” to each resource name, include the following in your kustomization.yaml:
After applying this configuration, a Service resource would be renamed to “KodeKloud-api-service-dev”:

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4. Common Annotation Transformation

If you need to add specific annotations to all resources, use the common annotations transformer. By setting the annotations in your kustomization.yaml, each resource will automatically include them. For example:
This transformation results in a Service resource similar to:

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Summary

The common transformations available in Kustomize include: These methods provide a scalable and systematic approach to maintaining consistent configurations across your Kubernetes resources.
The image lists common transformations for Kubernetes resources, including adding labels, prefixes/suffixes, namespaces, and annotations.
In summary, Kustomize transformers offer a robust and error-resistant way to apply common configurations—such as labels, namespaces, name modifications, and annotations—to your Kubernetes resources, ensuring that your deployments remain consistent and manageable across various environments.

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