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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.

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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.

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Common Transformers Overview

The image lists common transformations for Kubernetes resources, including adding labels, prefixes/suffixes, namespaces, and annotations.
TransformerField NamePurpose
Common LabelscommonLabelsAdd one or more labels to all resources
Name Prefix/SuffixnamePrefix
nameSuffix		Prepend or append text to resource names
NamespacenamespaceAssign a namespace to every resource
Common AnnotationscommonAnnotationsAdd one or more annotations to all resources

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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

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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
# …

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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.

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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.

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