creating-kubernetes-deployments

# Creating Kubernetes Deployments Generate production-ready Kubernetes manifests with health checks, resource limits, and security best practices. ## Quick Start ### Basic Deployment + Service ```yaml # deployment.yaml apiVersion: apps/v1 kind: Deployment metadata: name: my-api labels: app: my-api spec: replicas: 3 selector: matchLabels: app: my-api strategy: type: RollingUpdate rollingUpdate: maxSurge: 25% maxUnavailable: 25% template: metadata: labels: app: my-api spec: containers: - name: my-api image: my-registry/my-api:v1.0.0 ports: - containerPort: 8080 resources: requests: cpu: 100m memory: 256Mi limits: cpu: 500m memory: 512Mi livenessProbe: httpGet: path: /healthz port: 8080 initialDelaySeconds: 30 periodSeconds: 10 readinessProbe: httpGet: path: /readyz port: 8080 initialDelaySeconds: 5 periodSeconds: 5 --- apiVersion: v1 kind: Service metadata: name: my-api spec: type: ClusterIP selector: app: my-api ports: - port: 80 targetPort: 8080 ``` ## Deployment Strategies | Strategy | Use Case | Configuration | |----------|----------|---------------| | RollingUpdate | Zero-downtime updates | `maxSurge: 25%`, `maxUnavailable: 25%` | | Recreate | Stateful apps, incompatible versions | `type: Recreate` | | Blue-Green | Instant rollback | Two deployments, switch Service selector | | Canary | Gradual rollout | Multiple deployments with weighted traffic | ### Blue-Green Deployment ```yaml # Blue deployment (current production) apiVersion: apps/v1 kind: Deployment metadata: name: my-api-blue labels: app: my-api version: blue spec: replicas: 3 selector: matchLabels: app: my-api version: blue template: metadata: labels: app: my-api version: blue spec: containers: - name: my-api image: my-registry/my-api:v1.0.0 --- # Service points to blue apiVersion: v1 kind: Service metadata: name: my-api spec: selector: app: my-api version: blue # Switch to 'green' for deployment ports: - port: 80 targetPort: 8080 ``` ## Service Types | Type | Use Case | Access | |------|----------|--------| | ClusterIP | Internal services | `my-api.namespace.svc.cluster.local` | | NodePort | Development, debugging | `:` | | LoadBalancer | External traffic (cloud) | Cloud provider LB IP | | ExternalName | External service proxy | DNS CNAME | ## Ingress with TLS ```yaml apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: my-api-ingress annotations: cert-manager.io/cluster-issuer: letsencrypt-prod nginx.ingress.kubernetes.io/ssl-redirect: "true" spec: ingressClassName: nginx tls: - hosts: - api.example.com secretName: api-tls-secret rules: - host: api.example.com http: paths: - path: / pathType: Prefix backend: service: name: my-api port: number: 80 ``` ## Resource Limits **Always set resource requests and limits:** ```yaml resources: requests: # Guaranteed resources cpu: 100m # 0.1 CPU core memory: 256Mi limits: # Maximum allowed cpu: 500m # 0.5 CPU core memory: 512Mi ``` | Workload Type | CPU Request | Memory Request | CPU Limit | Memory Limit | |---------------|-------------|----------------|-----------|--------------| | Web API | 100m-500m | 256Mi-512Mi | 500m-1000m | 512Mi-1Gi | | Worker | 250m-1000m | 512Mi-1Gi | 1000m-2000m | 1Gi-2Gi | | Database | 500m-2000m | 1Gi-4Gi | 2000m-4000m | 4Gi-8Gi | ## Health Checks ### Liveness Probe (Is container running?) ```yaml livenessProbe: httpGet: path: /healthz port: 8080 initialDelaySeconds: 30 # Wait for app startup periodSeconds: 10 # Check every 10s timeoutSeconds: 5 # Timeout per check failureThreshold: 3 # Restart after 3 failures ``` ### Readiness Probe (Ready for traffic?) ```yaml readinessProbe: httpGet: path: /readyz port: 8080 initialDelaySeconds: 5 # Quick check after start periodSeconds: 5 # Check every 5s successThreshold: 1 # 1 success = ready failureThreshold: 3 # Remove from LB after 3 failures ``` ### Startup Probe (Slow-starting apps) ```yaml startupProbe: httpGet: path: /healthz port: 8080 initialDelaySeconds: 0 periodSeconds: 10 failureThreshold: 30 # Allow 5 minutes to start (30 * 10s) ``` ## Horizontal Pod Autoscaler ```yaml apiVersion: autoscaling/v2 kind: HorizontalPodAutoscaler metadata: name: my-api-hpa spec: scaleTargetRef: apiVersion: apps/v1 kind: Deployment name: my-api minReplicas: 2 maxReplicas: 10 metrics: - type: Resource resource: name: cpu target: type: Utilization averageUtilization: 70 - type: Resource resource: name: memory target: type: Utilization averageUtilization: 80 behavior: scaleDown: stabilizationWindowSeconds: 300 # Wait 5min before scale down ``` ## ConfigMaps and Secrets ### ConfigMap (Non-sensitive config) ```yaml apiVersion: v1 kind: ConfigMap metadata: name: my-api-config data: LOG_LEVEL: "info" API_ENDPOINT: "https://api.example.com" config.yaml: | server: port: 8080 features: enabled: true ``` ### Secret (Sensitive data - base64 encoded) ```yaml apiVersion: v1 kind: Secret metadata: name: my-api-secrets type: Opaque data: API_KEY: YXBpLWtleS1oZXJl # echo -n "api-key-here" | base64 DATABASE_URL: cG9zdGdyZXM6Ly8uLi4= # echo -n "postgres://..." | base64 ``` ### Using in Deployment ```yaml spec: containers: - name: my-api envFrom: - configMapRef: name: my-api-config - secretRef: name: my-api-secrets volumeMounts: - name: config-volume mountPath: /app/config volumes: - name: config-volume configMap: name: my-api-config ``` ## Instructions 1. **Gather Requirements** - Application name, container image, port - Replica count and resource requirements - Health check endpoints - External access requirements (Ingress/LoadBalancer) 2. **Generate Base Manifests** - Create Deployment with resource limits and probes - Create Service (ClusterIP for internal, LoadBalancer for external) - Add ConfigMap for configuration - Add Secret for sensitive data 3. **Add Production Features** - Configure Ingress with TLS if external access needed - Add HPA for auto-scaling - Add NetworkPolicy for security - Add PodDisruptionBudget for availability 4. **Validate and Apply** ```bash # Validate manifests kubectl apply -f manifests/ --dry-run=server # Apply to cluster kubectl apply -f manifests/ # Watch rollout kubectl rollout status deployment/my-api ``` ## Error Handling See `{baseDir}/references/errors.md` for comprehensive troubleshooting. | Error | Quick Fix | |-------|-----------| | ImagePullBackOff | Check image name, tag, registry credentials | | CrashLoopBackOff | Check logs: `kubectl logs ` | | OOMKilled | Increase memory limits | | Pending | Check resources: `kubectl describe pod ` | ## Examples See `{baseDir}/references/examples.md` for detailed walkthroughs. ## Resources - Kubernetes documentation: https://kubernetes.io/docs/ - kubectl reference: https://kubernetes.io/docs/reference/kubectl/ - Templates in `{baseDir}/assets/` - Scripts in `{baseDir}/scripts/`