Kubernetes Operations

Deploy and manage containerized applications on Kubernetes clusters.

When to Use This Skill

Use this skill when:

• Deploying applications to Kubernetes

• Managing pods, deployments, and services

• Configuring resource limits and scaling

• Troubleshooting Kubernetes workloads

• Setting up networking and ingress

Prerequisites

• kubectl installed and configured

• Access to a Kubernetes cluster

• Basic understanding of containers

Core Resources

Deployment

apiVersion: apps/v1 kind: Deployment metadata: name: myapp labels: app: myapp spec: replicas: 3 selector: matchLabels: app: myapp template: metadata: labels: app: myapp spec: containers: - name: myapp image: myapp:1.0.0 ports: - containerPort: 8080 resources: requests: memory: "128Mi" cpu: "100m" limits: memory: "256Mi" cpu: "500m" livenessProbe: httpGet: path: /health port: 8080 initialDelaySeconds: 10 periodSeconds: 10 readinessProbe: httpGet: path: /ready port: 8080 initialDelaySeconds: 5 periodSeconds: 5 env: - name: DATABASE_URL valueFrom: secretKeyRef: name: myapp-secrets key: database-url

Service

apiVersion: v1 kind: Service metadata: name: myapp spec: selector: app: myapp ports:

• port: 80 targetPort: 8080 type: ClusterIP

LoadBalancer for external access

apiVersion: v1 kind: Service metadata: name: myapp-external spec: selector: app: myapp ports:

• port: 80 targetPort: 8080 type: LoadBalancer

Ingress

apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: myapp annotations: nginx.ingress.kubernetes.io/rewrite-target: / 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

Configuration Management

ConfigMap

apiVersion: v1 kind: ConfigMap metadata: name: myapp-config data: config.yaml: | server: port: 8080 logging: level: info APP_ENV: production

Using ConfigMap

containers:

• name: myapp envFrom:
  • configMapRef: name: myapp-config volumeMounts:
  • name: config mountPath: /etc/config volumes:
• name: config configMap: name: myapp-config

Secret

apiVersion: v1 kind: Secret metadata: name: myapp-secrets type: Opaque stringData: database-url: postgres://user:pass@host:5432/db api-key: secret-key-value

Create secret from command line

kubectl create secret generic myapp-secrets
--from-literal=database-url='postgres://...'
--from-file=tls.crt=cert.pem

kubectl Commands

Resource Management

Apply configuration

kubectl apply -f deployment.yaml

Get resources

kubectl get pods kubectl get deployments kubectl get services kubectl get all -n myapp

Describe resource

kubectl describe pod myapp-xxx

Delete resource

kubectl delete -f deployment.yaml kubectl delete pod myapp-xxx

Edit resource

kubectl edit deployment myapp

Debugging

View logs

kubectl logs myapp-xxx kubectl logs -f myapp-xxx --tail=100 kubectl logs myapp-xxx -c sidecar # specific container

Execute command

kubectl exec -it myapp-xxx -- /bin/sh

Port forward

kubectl port-forward svc/myapp 8080:80 kubectl port-forward pod/myapp-xxx 8080:8080

View events

kubectl get events --sort-by='.lastTimestamp'

Debug pod

kubectl debug myapp-xxx -it --image=busybox

Scaling

Manual scaling

kubectl scale deployment myapp --replicas=5

Autoscaling

kubectl autoscale deployment myapp
--min=2 --max=10
--cpu-percent=80

Horizontal Pod Autoscaler

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: 80
• type: Resource resource: name: memory target: type: Utilization averageUtilization: 80

Persistent Storage

PersistentVolumeClaim

apiVersion: v1 kind: PersistentVolumeClaim metadata: name: myapp-data spec: accessModes: - ReadWriteOnce storageClassName: standard resources: requests: storage: 10Gi

Using PVC

containers:

• name: myapp volumeMounts:
  • name: data mountPath: /data volumes:
• name: data persistentVolumeClaim: claimName: myapp-data

StatefulSet

apiVersion: apps/v1 kind: StatefulSet metadata: name: postgres spec: serviceName: postgres replicas: 3 selector: matchLabels: app: postgres template: metadata: labels: app: postgres spec: containers: - name: postgres image: postgres:15 ports: - containerPort: 5432 volumeMounts: - name: data mountPath: /var/lib/postgresql/data volumeClaimTemplates:

• metadata: name: data spec: accessModes: ["ReadWriteOnce"] resources: requests: storage: 10Gi

Jobs and CronJobs

Job

apiVersion: batch/v1 kind: Job metadata: name: migration spec: template: spec: containers: - name: migrate image: myapp:1.0.0 command: ["./migrate.sh"] restartPolicy: Never backoffLimit: 3

CronJob

apiVersion: batch/v1 kind: CronJob metadata: name: backup spec: schedule: "0 2 * * *" jobTemplate: spec: template: spec: containers: - name: backup image: backup-tool:latest command: ["./backup.sh"] restartPolicy: OnFailure

Network Policies

apiVersion: networking.k8s.io/v1 kind: NetworkPolicy metadata: name: myapp-network-policy spec: podSelector: matchLabels: app: myapp policyTypes:

• Ingress
• Egress ingress:
• from:
  • podSelector: matchLabels: app: frontend ports:
  • protocol: TCP port: 8080 egress:
• to:
  • podSelector: matchLabels: app: database ports:
  • protocol: TCP port: 5432

Resource Quotas

apiVersion: v1 kind: ResourceQuota metadata: name: myapp-quota namespace: myapp spec: hard: requests.cpu: "10" requests.memory: 20Gi limits.cpu: "20" limits.memory: 40Gi pods: "20"

Rolling Updates

spec: strategy: type: RollingUpdate rollingUpdate: maxSurge: 1 maxUnavailable: 0

Update image

kubectl set image deployment/myapp myapp=myapp:2.0.0

Check rollout status

kubectl rollout status deployment/myapp

View history

kubectl rollout history deployment/myapp

Rollback

kubectl rollout undo deployment/myapp kubectl rollout undo deployment/myapp --to-revision=2

Common Issues

Issue: Pod Stuck in Pending

Problem: Pod won't start Solution: Check resource availability, node selector, PVC binding

kubectl describe pod myapp-xxx kubectl get events

Issue: CrashLoopBackOff

Problem: Container keeps restarting Solution: Check logs, verify entrypoint, check probes

kubectl logs myapp-xxx --previous kubectl describe pod myapp-xxx

Issue: Service Not Accessible

Problem: Cannot connect to service Solution: Check selector labels, verify endpoints exist

kubectl get endpoints myapp kubectl describe svc myapp

Issue: Image Pull Error

Problem: ImagePullBackOff Solution: Check image name, verify registry credentials

kubectl create secret docker-registry regcred
--docker-server=registry.example.com
--docker-username=user
--docker-password=pass

Best Practices

• Always set resource requests and limits

• Implement liveness and readiness probes

• Use namespaces for isolation

• Apply network policies for security

• Use ConfigMaps and Secrets for configuration

• Implement pod disruption budgets for availability

• Use labels consistently for organization

• Enable RBAC for access control

Related Skills

• helm-charts - Package management

• argocd-gitops - GitOps deployments

• kubernetes-hardening - Security