Transformers Demo

In this tutorial, you’ll learn how to apply common Kustomize transformers—labels, annotations, name prefixes/suffixes, namespaces, and image updates—across your Kubernetes manifests. We’ll use a simple API and database example to demonstrate each feature step by step.

Directory Layout

Our project structure separates API and database manifests into their own folders:

k8s/
├── api/
│   ├── api-depl.yaml
│   ├── api-service.yaml
│   └── kustomization.yaml
└── db/
    ├── db-config.yaml
    ├── db-depl.yaml
    ├── db-service.yaml
    └── kustomization.yaml

Each subdirectory’s kustomization.yaml declares its local resources. For example, api/kustomization.yaml:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - api-depl.yaml
  - api-service.yaml

And db/kustomization.yaml:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - db-config.yaml
  - db-depl.yaml
  - db-service.yaml

The root kustomization.yaml aggregates both:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - api/
  - db/

1. Global Labels with `commonLabels`

To tag all resources with department=engineering, add a commonLabels section at the root:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - api/
  - db/
commonLabels:
  department: engineering

Build the manifests:

kustomize build k8s/

Excerpt of the generated YAML shows the label applied everywhere:

apiVersion: v1
kind: ConfigMap
metadata:
  name: db-credentials
  labels:
    department: engineering
---
apiVersion: v1
kind: Service
metadata:
  name: api-service
  labels:
    department: engineering

2. Scoped Labels in Subdirectories

Labels in a subdirectory only affect its own resources. API folder example (api/kustomization.yaml):

commonLabels:
  feature: api

After rebuilding:

API resources include both department=engineering and feature=api.
DB resources remain only department=engineering.

Similarly, add feature: db to db/kustomization.yaml:

commonLabels:
  feature: db

3. Assigning a Namespace

To place all resources into a namespace (e.g., debugging), set namespace at the root:

namespace: debugging

Rebuild and notice each resource now has:

metadata:
  namespace: debugging

4. Name Prefixes and Suffixes

Global Prefix

In the root kustomization.yaml:

namePrefix: KodeKloud-

Every resource name is prefixed with KodeKloud-.

Subdirectory Suffixes

api/kustomization.yaml:
nameSuffix: -web
db/kustomization.yaml:
nameSuffix: -storage

Resulting resource names:

name: KodeKloud-api-deployment-web
name: KodeKloud-db-deployment-storage

5. Common Annotations

Add commonAnnotations at the root to include annotations globally:

commonAnnotations:
  logging: verbose

Each manifest’s metadata now contains:

annotations:
  logging: verbose

6. Overriding Container Images

Use the images transformer where needed. In db/kustomization.yaml, override the MongoDB image:

images:
  - name: mongo
    newName: postgres
    newTag: "4.2"

Always quote newTag so that it’s parsed as a string by Kustomize.

After building, the DB Deployment spec shows:

spec:
  containers:
    - name: mongo
      image: postgres:4.2

Only the specified image is updated; all other container images remain unchanged.

Kustomize Transformers at a Glance

Transformer	Scope	Example
commonLabels	Global/Sub	`department: engineering`
namespace	Global	`namespace: debugging`
namePrefix	Global	`KodeKloud-`
nameSuffix	Subdirectory	`-web`, `-storage`
commonAnnotations	Global	`logging: verbose`
images	Directory	Override `mongo` to `postgres:4.2`

Next, try these transformers hands-on to see how they simplify your Kubernetes deployments.

Introduction

Kustomize Basics

Secret/Config Generator

Other Commands

Kustomize Overview

Capstone Project

Directory Layout

1. Global Labels with `commonLabels`

2. Scoped Labels in Subdirectories

3. Assigning a Namespace

4. Name Prefixes and Suffixes

Global Prefix

Subdirectory Suffixes

5. Common Annotations

6. Overriding Container Images

Kustomize Transformers at a Glance

Links and References

Watch Video

Practice Lab

​Directory Layout

​1. Global Labels with commonLabels

​2. Scoped Labels in Subdirectories

​3. Assigning a Namespace

​4. Name Prefixes and Suffixes

​Global Prefix

​Subdirectory Suffixes

​5. Common Annotations

​6. Overriding Container Images

​Kustomize Transformers at a Glance

​Links and References

Watch Video

Practice Lab

Directory Layout

1. Global Labels with `commonLabels`

2. Scoped Labels in Subdirectories

3. Assigning a Namespace

4. Name Prefixes and Suffixes

Global Prefix

Subdirectory Suffixes

5. Common Annotations

6. Overriding Container Images

Kustomize Transformers at a Glance

Links and References