kubernetes-best-practices

Kubernetes Best Practices

This skill provides guidance for writing production-ready Kubernetes manifests and managing cloud-native applications.

Resource Management

Memory: Set requests and limits to the same value to ensure QoS class and prevent OOM kills.

CPU: Set requests only, omit limits to allow performance bursting and avoid throttling.

resources:
  requests:
    memory: "256Mi"
    cpu: "250m"
  limits:
    memory: "256Mi"
    # No CPU limit

Image Versioning

Always pin specific versions, never use :latest tag unless explicitly requested:

# Good
image: nginx:1.25.3

# Bad
image: nginx:latest

For immutability, consider pinning to specific digests.

Configuration Management

Secrets: Sensitive data (passwords, tokens, certificates) ConfigMaps: Non-sensitive configuration (feature flags, URLs, settings)

env:
  - name: DATABASE_URL
    valueFrom:
      secretKeyRef:
        name: app-secrets
        key: database-url
  - name: LOG_LEVEL
    valueFrom:
      configMapKeyRef:
        name: app-config
        key: log-level

Best practices:

• Never hardcode secrets in manifests
• Use external secret management (Sealed Secrets, External Secrets Operator)
• Rotate secrets regularly
• Limit access with RBAC

Workload Selection

Choose the appropriate workload type:

• Deployment: Stateless applications (web servers, APIs, microservices)
• StatefulSet: Stateful applications (databases, message queues)
• DaemonSet: Node-level services (log collectors, monitoring agents)
• Job/CronJob: Batch processing and scheduled tasks

Security Context

Always implement security best practices:

securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  fsGroup: 1000
  capabilities:
    drop:
      - ALL
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false

Security checklist:

• Run as non-root user
• Drop all capabilities by default
• Use read-only root filesystem
• Disable privilege escalation
• Implement network policies
• Scan images for vulnerabilities

Health Checks

Implement all three probe types:

Liveness: Restart container if unhealthy Readiness: Remove from service endpoints if not ready Startup: Allow slow-starting containers time to initialize

livenessProbe:
  httpGet:
    path: /healthz
    port: 8080
  initialDelaySeconds: 30
  periodSeconds: 10

readinessProbe:
  httpGet:
    path: /ready
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 5

startupProbe:
  httpGet:
    path: /startup
    port: 8080
  periodSeconds: 10
  failureThreshold: 30

High Availability

Replica counts: Set minimum 2 for production workloads

Pod Disruption Budgets: Maintain availability during voluntary disruptions

apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: app-pdb
spec:
  minAvailable: 2
  selector:
    matchLabels:
      app: web-app

Additional HA considerations:

• Use anti-affinity rules for pod distribution across nodes
• Configure graceful shutdown periods
• Implement horizontal pod autoscaling
• Set appropriate resource requests for scheduling

Namespace Organization

Use namespaces for environment isolation and apply resource quotas:

apiVersion: v1
kind: ResourceQuota
metadata:
  name: prod-quota
  namespace: production
spec:
  hard:
    requests.cpu: "100"
    requests.memory: 200Gi
    persistentvolumeclaims: "10"

Benefits: Logical separation, resource limits, RBAC boundaries, cost tracking

Labels and Annotations

Use consistent, recommended labels:

metadata:
  labels:
    app.kubernetes.io/name: myapp
    app.kubernetes.io/instance: myapp-prod
    app.kubernetes.io/version: "1.0.0"
    app.kubernetes.io/component: backend
    app.kubernetes.io/part-of: ecommerce
    app.kubernetes.io/managed-by: helm

Service Types

• ClusterIP: Internal cluster communication (default)
• NodePort: External access via node ports (dev/test)
• LoadBalancer: Cloud provider load balancer (production)
• ExternalName: DNS CNAME record (external services)

Storage

Choose appropriate storage class and access mode:

Access Modes:

• ReadWriteOnce (RWO): Single node read-write
• ReadOnlyMany (ROX): Multiple nodes read-only
• ReadWriteMany (RWX): Multiple nodes read-write

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: app-data
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: fast-ssd
  resources:
    requests:
      storage: 10Gi

Validation and Testing

Always validate before applying to production:

1. Client-side validation: kubectl apply --dry-run=client -f manifest.yaml
2. Server-side validation: kubectl apply --dry-run=server -f manifest.yaml
3. Test in staging: Deploy to non-production environment first
4. Monitor metrics: Watch resource usage and application health
5. Gradual rollout: Use rolling updates with health checks

Application Checklist

When creating or reviewing Kubernetes manifests:

• Resource requests and limits configured
• Specific image version pinned (not :latest)
• Secrets and ConfigMaps used for configuration
• Security context implemented (non-root, dropped capabilities)
• Health checks configured (liveness, readiness, startup)
• Pod Disruption Budget defined for HA workloads
• Consistent labels applied
• Appropriate workload type selected
• Namespace and resource quotas configured
• Validated with dry-run before applying