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README.md

Kubernetes Deployment Guide

This directory contains Kubernetes configuration files for deploying the Cronjob Manager application. This guide will help you understand and deploy the application in a Kubernetes environment.

Directory Structure

k8s/
├── configmap.yaml    # Application configuration
├── secret.yaml       # Sensitive information
├── deployment.yaml   # Application deployment
├── service.yaml      # Service configuration
├── ingress.yaml      # Ingress configuration
├── hpa.yaml         # Horizontal Pod Autoscaler
├── prometheus/         # Prometheus configuration
│   ├── prometheus-config.yaml
│   └── prometheus-deployment.yaml
└── grafana/           # Grafana configuration
    ├── grafana-deployment.yaml
    ├── grafana-datasource.yaml
    ├── grafana-secret.yaml
    └── grafana-ingress.yaml

Prerequisites

  • Kubernetes cluster (v1.20+)
  • kubectl CLI tool
  • Docker registry access
  • Nginx Ingress Controller
  • cert-manager (for SSL/TLS)

Configuration Files

1. ConfigMap (configmap.yaml)

Contains non-sensitive configuration data:

  • Application settings
  • Database connection details
  • Redis connection details
  • Timezone settings

2. Secret (secret.yaml)

Contains sensitive information (base64 encoded):

  • Database password
  • Redis password
  • JWT secret
  • SMTP credentials

3. Deployment (deployment.yaml)

Defines how the application should be deployed:

  • 3 replicas for high availability
  • Rolling update strategy
  • Resource limits and requests
  • Health checks (liveness and readiness probes)
  • Environment variables from ConfigMap and Secret

4. Service (service.yaml)

Exposes the application within the cluster:

  • ClusterIP type service
  • Port 80 forwarding to container port 8080

5. Ingress (ingress.yaml)

Configures external access:

  • SSL/TLS termination
  • Domain configuration
  • Nginx ingress settings

6. HPA (hpa.yaml)

Configures automatic scaling:

  • Min 3 replicas
  • Max 10 replicas
  • CPU and Memory based scaling

Monitoring Setup

The application includes comprehensive monitoring capabilities using Prometheus and Grafana.

1. Create Monitoring Namespace

kubectl create namespace monitoring

2. Deploy Prometheus

# Deploy Prometheus configurations
kubectl apply -f k8s/prometheus/

# Verify Prometheus deployment
kubectl get pods -n monitoring -l app=prometheus
kubectl get svc -n monitoring prometheus-service

3. Deploy Grafana

# Deploy Grafana configurations
kubectl apply -f k8s/grafana/

# Verify Grafana deployment
kubectl get pods -n monitoring -l app=grafana
kubectl get svc -n monitoring grafana-service

4. Access Monitoring Dashboards

  1. Prometheus UI

    • Access via port-forward: 
      kubectl port-forward svc/prometheus-service 9090:9090 -n monitoring
    • Open http://localhost:9090 in your browser

  2. Grafana Dashboard

5. Available Metrics

The application exposes the following metrics:

  1. Cronjob Execution Metrics
    • cronjob_execution_total: Total number of cronjob executions
    • cronjob_execution_duration_seconds: Duration of cronjob executions
    • cronjob_last_execution_timestamp: Timestamp of last execution
    • cronjob_errors_total: Total number of errors
    • cronjob_active_jobs: Number of currently active jobs
    • cronjob_scheduler_leader_info: Information about scheduler leadership

6. Grafana Dashboards

The default dashboard includes:

  • Cronjob execution statistics
  • Error rates and types
  • Active jobs monitoring
  • Execution duration metrics
  • Leadership status

7. Alerting

Configure alerts in Grafana for:

  • High error rates
  • Long execution durations
  • Job failures
  • Leadership changes

Deployment Steps

  1. Prepare Docker Image

    # Build the image
docker build -t your-registry.com/cronjob:latest .

# Push to registry
docker push your-registry.com/cronjob:latest

  2. Create Registry Secret

    kubectl create secret docker-registry regcred \
  --docker-server=your-registry.com \
  --docker-username=your-username \
  --docker-password=your-password

  3. Update Configuration

    • Modify configmap.yaml with your environment settings
    • Update secret.yaml with your encoded secrets: 
      # Example: Encoding secrets
echo -n "your-password" | base64
    • Update ingress.yaml with your domain

  4. Deploy Applications

    # Apply all configurations
kubectl apply -f k8s/

# Or apply individually
kubectl apply -f k8s/configmap.yaml
kubectl apply -f k8s/secret.yaml
kubectl apply -f k8s/deployment.yaml
kubectl apply -f k8s/service.yaml
kubectl apply -f k8s/ingress.yaml
kubectl apply -f k8s/hpa.yaml

  5. Verify Deployment

    # Check pods status
kubectl get pods -l app=cronjob

# Check service
kubectl get svc cronjob-service

# Check ingress
kubectl get ingress cronjob-ingress

# Check HPA
kubectl get hpa cronjob-hpa

Monitoring

  1. View Logs

    # Get pod logs
kubectl logs -l app=cronjob

# Follow logs from all pods
kubectl logs -f -l app=cronjob --all-containers

  2. Check Resources

    # Get pod details
kubectl describe pod -l app=cronjob

# Check HPA status
kubectl describe hpa cronjob-hpa

Troubleshooting

  1. Pod Issues

    # Check pod status
kubectl get pods -l app=cronjob

# Get pod details
kubectl describe pod [pod-name]

# Get pod logs
kubectl logs [pod-name]

  2. Service Issues

    # Check service endpoints
kubectl get endpoints cronjob-service

# Test service from another pod
kubectl run test-pod --rm -it --image=busybox -- wget -qO- http://cronjob-service

  3. Ingress Issues

    # Check ingress status
kubectl describe ingress cronjob-ingress

# Check ingress controller logs
kubectl logs -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx

Scaling

  • Manual Scaling

    # Scale deployment
kubectl scale deployment cronjob-deployment --replicas=5

  • Auto Scaling HPA will automatically scale based on CPU and Memory utilization:

    • Scales up when CPU or Memory > 80%
    • Scales down when CPU and Memory < 80%

Maintenance

  1. Update Image

    # Update deployment image
kubectl set image deployment/cronjob-deployment cronjob=your-registry.com/cronjob:new-tag

  2. Rolling Restart

    # Restart all pods
kubectl rollout restart deployment cronjob-deployment

  3. Backup Configuration

    # Export all resources
kubectl get all -l app=cronjob -o yaml > backup.yaml

Security Considerations

  1. Always use secrets for sensitive information
  2. Regularly rotate credentials
  3. Use network policies to restrict traffic
  4. Keep the Kubernetes cluster and ingress controller updated
  5. Monitor pod security policies
  6. Regularly scan container images for vulnerabilities

Development vs Production

For development environments, consider:

  • Reducing replica count
  • Lowering resource limits
  • Disabling HPA
  • Using different ingress settings
  • Setting debug level logs