deploy-to-kubernetes

Deploy to Kubernetes

Deploy containerized applications to Kubernetes with production-ready configurations including health checks, resource management, and automated rollouts.

When to Use

• Deploying new applications to Kubernetes clusters (EKS, GKE, AKS, self-hosted)
• Migrating from Docker Compose or traditional VMs to container orchestration
• Implementing zero-downtime rolling updates and rollbacks
• Managing application configuration and secrets in Kubernetes
• Setting up multi-environment deployments (dev, staging, production)
• Creating reusable Helm charts for application distribution

Inputs

• Required: Kubernetes cluster access (kubectl cluster-info)
• Required: Container images pushed to registry (Docker Hub, ECR, GCR, Harbor)
• Required: Application requirements (ports, environment variables, volumes)
• Optional: TLS certificates for HTTPS ingress
• Optional: Persistent storage requirements (StatefulSets, PVCs)
• Optional: Helm CLI for chart-based deployments

Procedure

See Extended Examples for complete configuration files and templates.

Step 1: Create Namespace and Resource Quotas

Organize applications into namespaces with resource limits and RBAC.

# Create namespace
kubectl create namespace myapp-prod

# Apply resource quota
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-quota
  namespace: myapp-prod
spec:
  hard:
    requests.cpu: "10"
    requests.memory: "20Gi"
    limits.cpu: "20"
    limits.memory: "40Gi"
    persistentvolumeclaims: "5"
    services.loadbalancers: "2"
---
apiVersion: v1
kind: LimitRange
metadata:
  name: default-limits
  namespace: myapp-prod
spec:
  limits:
  - default:
      cpu: "500m"
      memory: "512Mi"
    defaultRequest:
      cpu: "100m"
      memory: "128Mi"
    type: Container
EOF

# Create service account
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
  name: myapp
  namespace: myapp-prod
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: myapp-role
  namespace: myapp-prod
rules:
- apiGroups: [""]
  resources: ["configmaps", "secrets"]
  verbs: ["get", "list", "watch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: myapp-rolebinding
  namespace: myapp-prod
subjects:
- kind: ServiceAccount
  name: myapp
  namespace: myapp-prod
roleRef:
  kind: Role
  name: myapp-role
  apiGroup: rbac.authorization.k8s.io
EOF

# Verify namespace setup
kubectl get resourcequota -n myapp-prod
kubectl get limitrange -n myapp-prod
kubectl get sa -n myapp-prod

Expected: Namespace created with resource quotas limiting compute and storage. LimitRange sets default CPU/memory requests and limits. ServiceAccount configured with least-privilege RBAC.

On failure: For quota errors, verify cluster has sufficient resources with kubectl describe nodes. For RBAC errors, check cluster-admin permissions with kubectl auth can-i create role --namespace myapp-prod. Use kubectl describe on rejected resources to see quota/limit violations.

Step 2: Configure Application Secrets and ConfigMaps

Externalize configuration and sensitive data using ConfigMaps and Secrets.

# Create ConfigMap from literal values
kubectl create configmap myapp-config \
  --namespace=myapp-prod \
  --from-literal=LOG_LEVEL=info \
  --from-literal=API_TIMEOUT=30s \
  --from-literal=FEATURE_FLAGS='{"newUI":true,"betaAPI":false}'

# Create ConfigMap from file
cat > app.properties <<EOF
database.pool.size=20
cache.ttl=3600
retry.attempts=3
EOF

kubectl create configmap myapp-properties \
  --namespace=myapp-prod \
  --from-file=app.properties

# Create Secret for database credentials
kubectl create secret generic myapp-db-secret \
  --namespace=myapp-prod \
  --from-literal=username=appuser \
  --from-literal=password='sup3rs3cr3t!' \
  --from-literal=connection-string='postgresql://db.example.com:5432/myapp'

# Create TLS secret for ingress
kubectl create secret tls myapp-tls \
  --namespace=myapp-prod \
  --cert=path/to/tls.crt \
  --key=path/to/tls.key

# Verify secrets/configmaps
kubectl get configmap -n myapp-prod
kubectl get secret -n myapp-prod
kubectl describe configmap myapp-config -n myapp-prod

For more complex configurations, use YAML manifests:

# configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: myapp-config
  namespace: myapp-prod
data:
  nginx.conf: |
    server {
      listen 8080;
      location / {
        proxy_pass http://backend:3000;
        proxy_set_header Host $host;
      }
    }
  app-config.json: |
    {
      "logLevel": "info",
      "features": {
        "authentication": true,
        "metrics": true
      }
    }
---
# secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: myapp-secret
  namespace: myapp-prod
type: Opaque
stringData:  # Automatically base64 encoded
  api-key: "sk-1234567890abcdef"
  jwt-secret: "my-jwt-signing-key"

Expected: ConfigMaps store non-sensitive configuration, Secrets store credentials/keys. Values accessible to Pods via environment variables or volume mounts. TLS secrets properly formatted for Ingress resources.

On failure: For encoding issues, use stringData instead of data in YAML. For TLS secret errors, verify certificate and key format with openssl x509 -in tls.crt -text -noout. For access issues, check ServiceAccount RBAC permissions. View decoded secret with kubectl get secret myapp-secret -o jsonpath='{.data.api-key}' | base64 -d.

Step 3: Create Deployment with Health Checks and Resource Limits

Deploy application with production-ready configuration including probes and resource management.

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
  namespace: myapp-prod
  labels:
    app: myapp
    version: v1.0.0
spec:
  replicas: 3
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0  # Zero-downtime updates
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
        version: v1.0.0
      annotations:
        prometheus.io/scrape: "true"
        prometheus.io/port: "8080"
        prometheus.io/path: "/metrics"
    spec:
      serviceAccountName: myapp
      securityContext:
        runAsNonRoot: true
        runAsUser: 1000
        fsGroup: 1000
      containers:
      - name: myapp
        image: myregistry.io/myapp:v1.0.0
        imagePullPolicy: IfNotPresent
        ports:
        - name: http
          containerPort: 8080
          protocol: TCP
        env:
        - name: LOG_LEVEL
          valueFrom:
            configMapKeyRef:
              name: myapp-config
              key: LOG_LEVEL
        - name: DB_USERNAME
          valueFrom:
            secretKeyRef:
              name: myapp-db-secret
              key: username
        - name: DB_PASSWORD
          valueFrom:
            secretKeyRef:
              name: myapp-db-secret
              key: password
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        resources:
          requests:
            cpu: 250m
            memory: 256Mi
          limits:
            cpu: 500m
            memory: 512Mi
        livenessProbe:
          httpGet:
            path: /healthz
            port: http
          initialDelaySeconds: 30
          periodSeconds: 10
          timeoutSeconds: 5
          failureThreshold: 3
        readinessProbe:
          httpGet:
            path: /ready
            port: http
          initialDelaySeconds: 5
          periodSeconds: 5
          timeoutSeconds: 3
          failureThreshold: 2
        startupProbe:
          httpGet:
            path: /healthz
            port: http
          initialDelaySeconds: 0
          periodSeconds: 10
          timeoutSeconds: 3
          failureThreshold: 30  # 5 minutes for slow startup
        volumeMounts:
        - name: config
          mountPath: /etc/myapp
          readOnly: true
        - name: cache
          mountPath: /var/cache/myapp
      volumes:
      - name: config
        configMap:
          name: myapp-properties
      - name: cache
        emptyDir: {}
      imagePullSecrets:
      - name: registry-credentials

Apply and monitor deployment:

# Apply deployment
kubectl apply -f deployment.yaml

# Watch rollout status
kubectl rollout status deployment/myapp -n myapp-prod

# Check pod status
kubectl get pods -n myapp-prod -l app=myapp

# View pod logs
kubectl logs -n myapp-prod -l app=myapp --tail=50 -f

# Describe deployment for events
kubectl describe deployment myapp -n myapp-prod

# Check resource usage
kubectl top pods -n myapp-prod -l app=myapp

Expected: Deployment creates 3 replicas with rolling update strategy. Pods pass readiness probes before receiving traffic. Liveness probes restart unhealthy pods. Resource requests/limits prevent OOM kills. Logs show successful application startup.

On failure: For ImagePullBackOff, verify image exists and imagePullSecret is valid with kubectl get secret registry-credentials -o yaml. For CrashLoopBackOff, check logs with kubectl logs pod-name --previous. For probe failures, test endpoints manually with kubectl port-forward and curl localhost:8080/healthz. For OOMKilled pods, increase memory limits or investigate memory leaks.

Step 4: Expose Application with Services and Load Balancers

Create Service resources to expose applications internally and externally.

# service.yaml
apiVersion: v1
kind: Service
metadata:
  name: myapp
  namespace: myapp-prod
# ... (see EXAMPLES.md for complete configuration)

Apply and test services:

# Apply services
kubectl apply -f service.yaml

# Get service details
kubectl get svc -n myapp-prod

# ... (see EXAMPLES.md for complete configuration)

Expected: LoadBalancer Service provisions external LB with public IP/hostname. ClusterIP Service provides stable internal DNS. Endpoints list shows healthy Pod IPs. Curl requests succeed with expected responses.

On failure: For pending LoadBalancer, check cloud provider integration and quotas. For no endpoints, verify Pod labels match Service selector with kubectl get pods --show-labels. For connection refused, verify targetPort matches container port. Use kubectl port-forward to bypass Service layer for debugging.

Step 5: Configure Horizontal Pod Autoscaling

Implement automatic scaling based on CPU/memory or custom metrics.

# hpa.yaml
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp-hpa
  namespace: myapp-prod
# ... (see EXAMPLES.md for complete configuration)

Install metrics-server if not available:

# Install metrics-server
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

# Verify metrics-server
kubectl get deployment metrics-server -n kube-system
kubectl top nodes
# ... (see EXAMPLES.md for complete configuration)

Expected: HPA monitors CPU/memory metrics. When thresholds exceeded, replicas scale up to maxReplicas. When load decreases, replicas scale down gradually (stabilization window prevents flapping). Metrics visible with kubectl top.

On failure: For "unknown" metrics, verify metrics-server is running and Pods have resource requests defined. For no scaling, check current utilization is actually exceeding targets with kubectl top pods. For flapping, increase stabilizationWindowSeconds. For slow scale-up, reduce periodSeconds in scaleUp policies.

Step 6: Package Application with Helm Chart

Create reusable Helm chart for multi-environment deployments.

# Create Helm chart structure
helm create myapp-chart
cd myapp-chart

# Edit Chart.yaml
cat > Chart.yaml <<EOF
# ... (see EXAMPLES.md for complete configuration)

Expected: Helm chart packages all Kubernetes resources with templated values. Dry-run shows rendered manifests. Install deploys all resources in correct order. Upgrades perform rolling updates. Rollback reverts to previous revision.

On failure: For template errors, run helm template . to render locally without installing. For dependency issues, run helm dependency update. For value override failures, verify YAML path exists in values.yaml. Use helm get manifest myapp -n myapp-prod to see actual deployed resources.

Validation

• Pods in Running state with all containers ready
• Readiness probes pass before Pods added to Service endpoints
• Liveness probes restart unhealthy containers automatically
• Resource requests and limits prevent OOM kills and node overcommit
• Secrets and ConfigMaps mounted correctly with expected values
• Services resolve via DNS (cluster.local) from other Pods
• LoadBalancer/Ingress accessible from external networks
• HPA scales replicas up under load and down when idle
• Rolling updates complete with zero downtime
• Logs collected and accessible via kubectl logs or centralized logging

Common Pitfalls

• Missing readiness probes: Pods receive traffic before fully started. Always implement readiness probes that verify application dependencies.

• Insufficient startup time: Fast liveness probes kill slow-starting apps. Use startupProbe with generous failureThreshold for initialization.

• No resource limits: Pods consume unlimited CPU/memory causing node instability. Always set requests and limits.

• Hardcoded configuration: Environment-specific values in manifests prevent reuse. Use ConfigMaps, Secrets, and Helm values.

• Default service account: Pods have unnecessary cluster permissions. Create dedicated ServiceAccounts with minimal RBAC.

• No rolling update strategy: Deployments recreate all Pods simultaneously causing downtime. Use RollingUpdate with maxUnavailable: 0.

• Secrets in version control: Sensitive data committed to Git. Use sealed-secrets, external-secrets-operator, or vault.

• No pod disruption budget: Cluster maintenance drains nodes and breaks service. Create PodDisruptionBudget to ensure minimum available replicas.

Related Skills

• setup-docker-compose - Container orchestration fundamentals before Kubernetes
• containerize-mcp-server - Creating container images for deployment
• write-helm-chart - Advanced Helm chart development
• manage-kubernetes-secrets - SealedSecrets and external-secrets-operator
• configure-ingress-networking - NGINX Ingress and cert-manager setup
• implement-gitops-workflow - ArgoCD/Flux for declarative deployments
• setup-container-registry - Image registry integration