Kustomize

myapp/
├── base/
│   ├── kustomization.yaml
│   ├── deployment.yaml
│   ├── service.yaml
│   └── configmap.yaml
└── overlays/
    ├── development/
    │   ├── kustomization.yaml
    │   └── replica-patch.yaml
    ├── staging/
    │   ├── kustomization.yaml
    │   └── namespace.yaml
    └── production/
        ├── kustomization.yaml
        ├── replica-patch.yaml
        └── resource-patch.yaml

# base/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - deployment.yaml
  - service.yaml
  - configmap.yaml

commonLabels:
  app: myapp
  
commonAnnotations:
  managed-by: kustomize

# base/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:latest
        ports:
        - containerPort: 8080
        resources:
          requests:
            memory: "64Mi"
            cpu: "100m"
          limits:
            memory: "128Mi"
            cpu: "200m"

# overlays/development/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../base

namespace: myapp-dev

namePrefix: dev-

commonLabels:
  environment: development

images:
  - name: myapp
    newTag: dev-latest

# overlays/production/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../base

namespace: myapp-prod

namePrefix: prod-

commonLabels:
  environment: production

replicas:
  - name: myapp
    count: 5

images:
  - name: myapp
    newName: registry.example.com/myapp
    newTag: v2.0.0

patches:
  - path: resource-patch.yaml

# overlays/production/resource-patch.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
      - name: myapp
        resources:
          requests:
            memory: "256Mi"
            cpu: "500m"
          limits:
            memory: "512Mi"
            cpu: "1000m"

# kustomization.yaml
patches:
  - target:
      kind: Deployment
      name: myapp
    patch: |-
      - op: replace
        path: /spec/replicas
        value: 5
      - op: add
        path: /spec/template/spec/containers/0/env
        value:
          - name: LOG_LEVEL
            value: info

# kustomization.yaml
patches:
  - patch: |-
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: myapp
      spec:
        replicas: 3
    target:
      kind: Deployment
      name: myapp

# kustomization.yaml
configMapGenerator:
  - name: myapp-config
    literals:
      - APP_ENV=production
      - LOG_LEVEL=info
    files:
      - config.yaml
    envs:
      - config.env
    options:
      disableNameSuffixHash: false

# kustomization.yaml
secretGenerator:
  - name: myapp-secrets
    literals:
      - api-key=secret123
    files:
      - tls.crt
      - tls.key
    type: kubernetes.io/tls

# kustomization.yaml
images:
  # Change tag
  - name: myapp
    newTag: v2.0.0
  
  # Change registry
  - name: myapp
    newName: registry.example.com/myapp
    newTag: v2.0.0
  
  # Use digest
  - name: myapp
    digest: sha256:abc123...

# kustomization.yaml
namePrefix: prod-
nameSuffix: -v2

# kustomization.yaml
namespace: production

# kustomization.yaml
commonLabels:
  app.kubernetes.io/name: myapp
  app.kubernetes.io/environment: production

commonAnnotations:
  example.com/owner: team-a

# kustomization.yaml
replicas:
  - name: myapp
    count: 5
  - name: worker
    count: 3

# components/monitoring/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1alpha1
kind: Component

resources:
  - servicemonitor.yaml

patches:
  - patch: |-
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: myapp
      spec:
        template:
          metadata:
            annotations:
              prometheus.io/scrape: "true"
              prometheus.io/port: "8080"

# overlays/production/kustomization.yaml
components:
  - ../../components/monitoring

# kustomization.yaml
resources:
  # Remote Git repository
  - https://github.com/org/manifests//base?ref=v1.0.0
  
  # Remote URL
  - https://raw.githubusercontent.com/org/repo/main/deployment.yaml

# Build and view output
kubectl kustomize overlays/production

# Apply to cluster
kubectl apply -k overlays/production

# Delete resources
kubectl delete -k overlays/production

# View diff
kubectl diff -k overlays/production

# Build with standalone kustomize
kustomize build overlays/production

# Build and apply
kustomize build overlays/production | kubectl apply -f -

# kustomization.yaml
helmCharts:
  - name: prometheus
    repo: https://prometheus-community.github.io/helm-charts
    version: 25.0.0
    releaseName: prometheus
    namespace: monitoring
    valuesFile: values.yaml
    includeCRDs: true

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - deployment.yaml

replacements:
  - source:
      kind: ConfigMap
      name: myapp-config
      fieldPath: data.APP_VERSION
    targets:
      - select:
          kind: Deployment
          name: myapp
        fieldPaths:
          - spec.template.spec.containers.[name=myapp].image
        options:
          delimiter: ':'
          index: 1

commonLabels:
  app: myapp
configurations:
  - labelExclusions.yaml

git status && git diff --stat
kubectl diff -f manifest.yaml