Code snippets — Kubernetes For Backend Engineers

snippet-2.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-api
  template:
    metadata:
      labels:
        app: my-api
    spec:
      containers:
      - name: api
        image: myapp:1.0.0
        resources:
          requests:
            memory: "128Mi"
            cpu: "250m"
          limits:
            memory: "512Mi"
            cpu: "500m"
        readinessProbe:
          httpGet:
            path: /health
            port: 8080
          initialDelaySeconds: 5
          periodSeconds: 10

snippet-3.yaml

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

snippet-4.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: api-config
data:
  LOG_LEVEL: "info"
  MAX_CONNECTIONS: "100"

---

apiVersion: v1
kind: Secret
metadata:
  name: api-secrets
type: Opaque
data:
  # base64 encoded values
  DB_PASSWORD: cGFzc3dvcmQxMjM=

snippet-5.yaml

env:
- name: LOG_LEVEL
  valueFrom:
    configMapKeyRef:
      name: api-config
      key: LOG_LEVEL
- name: DB_PASSWORD
  valueFrom:
    secretKeyRef:
      name: api-secrets
      key: DB_PASSWORD

snippet-6.yaml

spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1        # Can have 1 extra pod during update
      maxUnavailable: 0  # Never have fewer than desired count

snippet-7.yaml

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

snippet.sh

# See what's running
kubectl get pods -n my-namespace
kubectl get deployments

# Debug a pod
kubectl describe pod <pod-name>
kubectl logs <pod-name> --tail=100 -f

# Execute into a container
kubectl exec -it <pod-name> -- /bin/sh

# Apply a manifest
kubectl apply -f deployment.yaml

# Rollback a deployment
kubectl rollout undo deployment/api-deployment

# Check rollout status
kubectl rollout status deployment/api-deployment

snippet.txt

You declare desired state → Kubernetes reconciles → Actual state matches desired state

snippet.yaml

apiVersion: v1
kind: Pod
metadata:
  name: my-api
spec:
  containers:
  - name: api
    image: myapp:1.0.0
    ports:
    - containerPort: 8080