Common Transformers

In this lesson, we’ll explore Kustomize’s built-in Common Transformers. They let you apply shared modifications—such as labels, prefixes/suffixes, namespaces, and annotations—to all of your Kubernetes manifests without touching each file manually.

The Challenge

Imagine you have these two resource definitions:

# db-depl.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      component: api
  template:
    metadata:
      labels:
        component: api
    spec:
      containers:
        - name: nginx
          image: nginx

# db-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: db-service
spec:
  selector:
    component: db-depl
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017
  type: LoadBalancer

Your goal is to:

Add a shared label: org: KodeKloud
Append -dev to every resource name

Manually editing each file is tedious and error-prone. Kustomize simplifies this with common transformers.

Common Transformers Overview

The image lists common transformations for Kubernetes resources, including adding labels, prefixes/suffixes, namespaces, and annotations.

Transformer	Field Name	Purpose
Common Labels	`commonLabels`	Add one or more labels to all resources
Name Prefix/Suffix	`namePrefix` `nameSuffix`	Prepend or append text to resource names
Namespace	`namespace`	Assign a namespace to every resource
Common Annotations	`commonAnnotations`	Add one or more annotations to all resources

1. Apply Common Labels

Add the commonLabels block to your kustomization.yaml:

resources:
  - db-depl.yaml
  - db-service.yaml

commonLabels:
  org: KodeKloud

When you run kustomize build, these labels will be merged into every resource’s metadata.labels.

Generated output (Service example):

apiVersion: v1
kind: Service
metadata:
  name: db-service
  labels:
    org: KodeKloud
spec:
  selector:
    component: db-depl
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017
  type: LoadBalancer

2. Set a Namespace

To place all resources into a specific namespace:

namespace: lab

Resulting snippet:

apiVersion: v1
kind: Service
metadata:
  name: db-service
  namespace: lab
  labels:
    org: KodeKloud
# …

3. Add Name Prefix & Suffix

Prepend and append text to every resource name:

namePrefix: kodekloud-
nameSuffix: -dev

Rendered output:

apiVersion: v1
kind: Service
metadata:
  name: kodekloud-db-service-dev
  labels:
    org: KodeKloud
  namespace: lab
# …

Choosing very long prefixes or suffixes can push resource names over Kubernetes’ max-length limit (63 characters). Always verify final name lengths.

4. Inject Common Annotations

Include the following to add annotations across all manifests:

commonAnnotations:
  branch: master

Sample annotation merge:

metadata:
  annotations:
    branch: master
# …

By combining these four settings in a single kustomization.yaml, you can transform your base manifests consistently and safely—no manual edits required.

Common Transformers

The Challenge

Common Transformers Overview

1. Apply Common Labels

2. Set a Namespace

3. Add Name Prefix & Suffix

4. Inject Common Annotations

Links and References

Watch Video

​The Challenge

​Common Transformers Overview

​1. Apply Common Labels

​2. Set a Namespace

​3. Add Name Prefix & Suffix

​4. Inject Common Annotations

​Links and References

Watch Video

The Challenge

Common Transformers Overview

1. Apply Common Labels

2. Set a Namespace

3. Add Name Prefix & Suffix

4. Inject Common Annotations

Links and References