Kubernetes Patterns

Kubernetes Patterns

Deployment with Probes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
  labels:
    app: myapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
        - name: myapp
          image: myapp:1.2.3
          ports:
            - containerPort: 8080
          resources:
            requests:
              cpu: 100m
              memory: 128Mi
            limits:
              cpu: 500m
              memory: 512Mi
          readinessProbe:
            httpGet:
              path: /ready
              port: 8080
            initialDelaySeconds: 5
            periodSeconds: 10
            failureThreshold: 3
          livenessProbe:
            httpGet:
              path: /health
              port: 8080
            initialDelaySeconds: 15
            periodSeconds: 20
          envFrom:
            - configMapRef:
                name: myapp-config
            - secretRef:
                name: myapp-secrets

Service

apiVersion: v1
kind: Service
metadata:
  name: myapp
spec:
  selector:
    app: myapp
  ports:
    - port: 80
      targetPort: 8080
  type: ClusterIP

Ingress (nginx)

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myapp
  annotations:
    nginx.ingress.kubernetes.io/rate-limit: "100"
    cert-manager.io/cluster-issuer: letsencrypt-prod
spec:
  ingressClassName: nginx
  tls:
    - hosts:
        - myapp.example.com
      secretName: myapp-tls
  rules:
    - host: myapp.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: myapp
                port:
                  number: 80

HorizontalPodAutoscaler

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp
  minReplicas: 2
  maxReplicas: 10
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70

PodDisruptionBudget

apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: myapp
spec:
  minAvailable: 2
  selector:
    matchLabels:
      app: myapp

ConfigMap + Secret

apiVersion: v1
kind: ConfigMap
metadata:
  name: myapp-config
data:
  LOG_LEVEL: info
  PORT: "8080"
---
apiVersion: v1
kind: Secret
metadata:
  name: myapp-secrets
type: Opaque
stringData:
  DATABASE_URL: postgres://user:pass@db:5432/myapp
  JWT_SECRET: changeme

ResourceQuota (namespace level)

apiVersion: v1
kind: ResourceQuota
metadata:
  name: team-quota
  namespace: team-a
spec:
  hard:
    requests.cpu: "4"
    requests.memory: 8Gi
    limits.cpu: "8"
    limits.memory: 16Gi
    pods: "20"

Key Rules

• Always set resource requests AND limits
• Use minAvailable PDB to ensure availability during rolling updates
• Prefer readinessProbe over livenessProbe for startup — liveness restarts the pod
• Never use latest image tag in production
• Use topologySpreadConstraints to spread pods across AZs