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README.md

Nginx JSON API Kubernetes Deployment

This deployment provides a Kubernetes-based solution for serving JSON data via a RESTful API, with automatic hourly refresh capabilities.

Architecture

  • FastAPI: Python RESTful API that generates and serves JSON data
  • Nginx: Reverse proxy that forwards requests to the FastAPI backend
  • Background Thread: Automatically refreshes the JSON file every hour
  • Kubernetes: Container orchestration for deployment and scaling

Components

Application Files

  • kernel_service.py: FastAPI application with JSON generation and serving logic
  • requirements.txt: Python dependencies
  • nginx.conf: Nginx configuration for reverse proxy
  • start.sh: Startup script that launches both nginx and the API
  • Dockerfile: Container image definition

Kubernetes Files

  • nginx-deployment.yml: Kubernetes Deployment configuration
  • nginx-service.yml: Kubernetes Service configuration (NodePort on port 30080)

Features

  1. Automatic JSON Generation: Generates initial JSON if file doesn't exist
  2. Hourly Refresh: Automatically reloads JSON file every hour
  3. RESTful API: Multiple endpoints for accessing JSON data
  4. Health Checks: Built-in health and readiness probes
  5. Path-based Access: Access nested JSON data via path parameters

API Endpoints

  • GET /: API information and status
  • GET /health: Health check endpoint
  • GET /api/data: Get all JSON data
  • GET /api/data/{path}: Get specific section by path (e.g., /api/data/data/items/0)
  • POST /api/refresh: Manually trigger JSON refresh

Deployment Steps

1. Build Docker Image

cd nginx_kuber
docker build -t nginx-json-api:latest .

2. Load Image to Kubernetes Cluster

If using a local cluster (like minikube or kind):

# For minikube
minikube image load nginx-json-api:latest

# For kind
kind load docker-image nginx-json-api:latest

Or push to a container registry and update the image reference in nginx-deployment.yml.

3. Deploy to Kubernetes

kubectl apply -f nginx-deployment.yml
kubectl apply -f nginx-service.yml

4. Verify Deployment

# Check deployment status
kubectl get deployments nginx-json-api

# Check pods
kubectl get pods -l app=nginx-json-api

# Check service
kubectl get svc nginx-json-api

# View logs
kubectl logs -l app=nginx-json-api

5. Access the API

If using NodePort (default):

  • Get node IP: kubectl get nodes -o wide
  • Access API: http://<NODE_IP>:30080

Or port-forward:

kubectl port-forward svc/nginx-json-api 8080:80
# Then access at http://localhost:8080

Customization

Modify JSON Generation

Edit the generate_json() function in kernel_service.py to customize the JSON structure.

Change Refresh Interval

Modify the sleep duration in the refresh_json_periodically() function (currently 3600 seconds = 1 hour).

External JSON File Updates

The application watches for file changes. If you have an external process that updates /app/data/reference.json, the API will pick it up on the next hourly refresh, or you can trigger a manual refresh via POST /api/refresh.

Persistent Storage

To persist JSON data across pod restarts, modify nginx-deployment.yml to use a PersistentVolumeClaim instead of emptyDir.

Environment Variables

  • JSON_FILE_PATH: Path to the JSON file (default: /app/data/reference.json)
  • API_PORT: Port for FastAPI backend (default: 8000)

Troubleshooting

  1. Check pod logs: kubectl logs -l app=nginx-json-api
  2. Check pod status: kubectl describe pod -l app=nginx-json-api
  3. Test API directly: kubectl exec -it <pod-name> -- curl http://localhost:80/health
  4. Verify JSON file: kubectl exec -it <pod-name> -- cat /app/data/reference.json