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In this guide, you’ll learn how to structure and configure the kustomization.yaml file for managing Kubernetes manifests with Kustomize. We’ll cover directory setup, key fields, building overlays, and deploying your customized resources.
Ensure you have Kustomize installed and available in your PATH. You can verify with:
kustomize version

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Directory Structure

Place your manifests and kustomization.yaml in a folder (e.g., k8s/). Only the kustomization.yaml file is processed directly—other YAMLs are referenced as resources.
The image shows a directory named "k8s" containing three YAML files: "nginx-depl.yml," "nginx-service.yml," and "kustomization.yaml."

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kustomization.yaml Fields

Here are the core sections you’ll use most often:
FieldPurposeExample
resourcesLists input Kubernetes YAML manifests- nginx-deployment.yaml
commonLabelsAdds identical labels to every resource in buildcompany: KodeKloud

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Configuring Resources and Labels

Create or update kustomization.yaml with your manifests and desired transformations: 
# kustomization.yaml
resources:
  - nginx-deployment.yaml
  - nginx-service.yaml

commonLabels:
  company: KodeKloud
  • resources: Relative paths to each manifest file.
  • commonLabels: A map of labels automatically injected into all output resources.
Keep your file names consistent (e.g., nginx-service.yaml vs. nginx-service.yml) to avoid missing resources during kustomize build.

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Generating Customized Manifests

Run the following command from the parent directory: 
kustomize build k8s/
This command:
  1. Reads k8s/kustomization.yaml.
  2. Imports listed resources.
  3. Applies commonLabels and other transformations.
  4. Emits the merged YAML to stdout.

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Sample Output

apiVersion: v1
kind: Service
metadata:
  name: nginx-loadbalancer-service
  labels:
    company: KodeKloud
spec:
  type: LoadBalancer
  ports:
    - port: 80
      targetPort: 3000
      protocol: TCP
  selector:
    company: KodeKloud
    component: nginx
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    company: KodeKloud
spec:
  replicas: 1
  selector:
    matchLabels:
      company: KodeKloud
      component: nginx
  template:
    metadata:
      labels:
        company: KodeKloud
        component: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
Notice each resource now carries company: KodeKloud. You can apply this directly to your cluster: 
kustomize build k8s/ | kubectl apply -f -
The image is a slide explaining the use of Kustomize in Kubernetes, detailing how it manages manifests and customizations, and the function of the kustomize build command.

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