Kubernetes Manifests
Understanding and writing Kubernetes manifest files.
Basic Structure
apiVersion: v1 kind: Pod metadata: name: my-app namespace: default labels: app: my-app spec: containers:
- name: app
image: nginx:latest
ports:
- containerPort: 80
Common Resource Types
Deployment
apiVersion: apps/v1 kind: Deployment metadata: name: my-app spec: replicas: 3 selector: matchLabels: app: my-app template: metadata: labels: app: my-app spec: containers: - name: app image: myapp:1.0.0 resources: requests: memory: "64Mi" cpu: "250m" limits: memory: "128Mi" cpu: "500m"
Service
apiVersion: v1 kind: Service metadata: name: my-app-service spec: selector: app: my-app ports:
- protocol: TCP port: 80 targetPort: 8080 type: LoadBalancer
ConfigMap
apiVersion: v1 kind: ConfigMap metadata: name: app-config data: database.url: "postgres://db:5432" log.level: "info"
Secret
apiVersion: v1 kind: Secret metadata: name: app-secrets type: Opaque data: password: cGFzc3dvcmQxMjM= # base64 encoded
Best Practices
Resource Requests and Limits
Always define resource requests and limits:
resources: requests: memory: "64Mi" cpu: "250m" limits: memory: "128Mi" cpu: "500m"
Liveness and Readiness Probes
livenessProbe: httpGet: path: /healthz port: 8080 initialDelaySeconds: 30 periodSeconds: 10
readinessProbe: httpGet: path: /ready port: 8080 initialDelaySeconds: 5 periodSeconds: 5
Labels and Selectors
Use consistent labeling:
metadata: labels: app: my-app version: v1 environment: production
Validation
Validate manifest syntax
kubectl apply --dry-run=client -f manifest.yaml
Validate with kubeconform
kubeconform manifest.yaml
Validate against live cluster
kubectl apply --dry-run=server -f manifest.yaml