Kubernetes Cheatsheet

kubectl Essentials

Apply & Inspect

kubectl apply -f file.yaml      # create/update
kubectl get pods -o wide        # list with node/IP
kubectl get all                 # everything in namespace
kubectl describe pod web        # events + spec
kubectl delete -f file.yaml
kubectl explain deployment.spec # schema docs

Debug

kubectl logs -f web             # follow logs
kubectl logs web --previous     # crashed container
kubectl exec -it web -- sh      # shell in
kubectl port-forward svc/web 8080:80
kubectl get events --sort-by=.lastTimestamp
kubectl top pods                # live CPU/mem

Namespaces & Context

kubectl create namespace staging
kubectl get pods -n staging
kubectl config set-context --current --namespace=staging
kubectl config get-contexts
kubectl config use-context prod

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 3
  selector:
    matchLabels: { app: web }
  template:
    metadata:
      labels: { app: web }
    spec:
      containers:
        - name: web
          image: ghcr.io/acme/web:1.4.0
          ports:
            - containerPort: 8080

Service Types

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

kubectl expose deployment web --port=80 --target-port=8080

Config & Secrets

kubectl create configmap app-config \
  --from-literal=LOG_LEVEL=info
kubectl create secret generic app-secret \
  --from-literal=DB_PASSWORD=s3cr3t

# inject into container spec
envFrom:
  - configMapRef: { name: app-config }
env:
  - name: DB_PASSWORD
    valueFrom:
      secretKeyRef:
        name: app-secret
        key: DB_PASSWORD

Rollouts

kubectl set image deployment/web web=repo/web:1.5.0
kubectl rollout status deployment/web
kubectl rollout history deployment/web
kubectl rollout undo deployment/web
kubectl scale deployment/web --replicas=5

Probes & Resources

livenessProbe:
  httpGet: { path: /healthz, port: 8080 }
  initialDelaySeconds: 10
  periodSeconds: 10
readinessProbe:
  httpGet: { path: /ready, port: 8080 }
  periodSeconds: 5
resources:
  requests: { cpu: "250m", memory: "256Mi" }
  limits:   { cpu: "500m", memory: "512Mi" }

Readiness gates traffic; liveness restarts the container. Don't point liveness at external dependencies.

Autoscaling & Ingress

kubectl autoscale deployment web \
  --cpu-percent=70 --min=3 --max=20
kubectl get hpa

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: web
spec:
  ingressClassName: nginx
  rules:
    - host: app.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: web
                port: { number: 80 }