# CDN Configuration

This directory contains Kubernetes configurations for Content Delivery Network (CDN) setup to optimize delivery of static assets and audio files.

## Overview

CDN configuration provides:
- **Faster asset delivery** through edge caching
- **Reduced origin server load**
- **Better global performance** with geographically distributed caching
- **Optimized caching** for different asset types

## Components

### nginx-cdn-config
- Optimized nginx configuration for CDN integration
- Long cache headers for static assets
- CORS headers for cross-origin requests
- Range request support for audio/video streaming

### cdn-configmap
- General CDN configuration
- Provider selection
- Cache TTL settings
- Feature toggles

### Provider-Specific Configs
- **cloudflare-config.yaml**: Cloudflare CDN configuration
- **cloudfront-config.yaml**: AWS CloudFront CDN configuration

## Supported CDN Providers

### Cloudflare
- **Pros**: Easy setup, free tier, DDoS protection, global network
- **Cons**: Limited customization on free tier
- **Best for**: Small to medium deployments

### AWS CloudFront
- **Pros**: Highly customizable, integrates with AWS services, pay-per-use
- **Cons**: More complex setup, AWS account required
- **Best for**: AWS-based infrastructure

### Generic CDN
- **Pros**: Works with any CDN provider
- **Cons**: Manual configuration required
- **Best for**: Custom CDN solutions

## Deployment

### 1. Apply nginx CDN Configuration

```bash
kubectl apply -f k8s/cdn/nginx-cdn-config.yaml
```

Update frontend deployment to use this config:

```yaml
volumeMounts:
- name: nginx-cdn-config
  mountPath: /etc/nginx/conf.d/cdn.conf
  subPath: nginx-cdn.conf
volumes:
- name: nginx-cdn-config
  configMap:
    name: nginx-cdn-config
```

### 2. Apply CDN ConfigMap

```bash
kubectl apply -f k8s/cdn/cdn-configmap.yaml
```

### 3. Configure CDN Provider

#### Cloudflare

1. Update `cloudflare-config.yaml` with your zone ID
2. Create secret with API token:
   ```bash
   kubectl create secret generic cloudflare-secrets \
     --from-literal=api-token=your-api-token \
     -n veza-production
   ```
3. Apply configuration:
   ```bash
   kubectl apply -f k8s/cdn/cloudflare-config.yaml
   ```

#### AWS CloudFront

1. Update `cloudfront-config.yaml` with your distribution ID
2. Create secret with AWS credentials:
   ```bash
   kubectl create secret generic aws-secrets \
     --from-literal=access-key-id=your-key \
     --from-literal=secret-access-key=your-secret \
     -n veza-production
   ```
3. Apply configuration:
   ```bash
   kubectl apply -f k8s/cdn/cloudfront-config.yaml
   ```

## Configuration

### Cache TTL Settings

Edit `cdn-configmap.yaml` to adjust cache TTLs:

```yaml
# Static assets (JS, CSS, images, fonts)
cdn-cache-ttl: "31536000"  # 1 year

# Audio files
cdn-audio-cache-ttl: "2592000"  # 30 days
```

### Enable/Disable CDN Features

```yaml
# Enable CDN for static assets
cdn-assets-enabled: "true"

# Enable CDN for audio files
cdn-audio-enabled: "true"

# Enable CDN for images
cdn-images-enabled: "true"
```

## Integration with Services

### Frontend

The frontend should use CDN URLs for static assets. Update environment variables:

```bash
VITE_CDN_URL=https://cdn.veza.com
VITE_CDN_ENABLED=true
```

### Backend API

The backend CDN service (`internal/services/cdn_service.go`) can generate CDN URLs:

```go
cdnService := services.NewCDNService(services.CDNConfig{
    Provider: services.CDNProviderCloudflare,
    BaseURL:  "https://cdn.veza.com",
    Enabled:  true,
})

assetURL := cdnService.GetAssetURL("images", "logo.png")
audioURL := cdnService.GetAudioURL("track-123", "song.mp3")
```

## Cache Invalidation

### Manual Invalidation

```bash
# Invalidate specific paths
kubectl exec -it deployment/veza-backend-api -n veza-production -- \
  /app/veza-api cdn invalidate /static/js/app.js /audio/track-123/song.mp3
```

### Automatic Invalidation

The backend CDN service supports automatic cache invalidation on content updates. Configure in `cdn-configmap.yaml`:

```yaml
cdn-invalidation-on-update: "true"
```

## Testing

### Verify CDN Headers

```bash
# Check static asset headers
curl -I https://cdn.veza.com/static/js/app.js

# Should see:
# Cache-Control: public, immutable, max-age=31536000
# X-CDN-Cache-Status: HIT
```

### Test CORS

```bash
# Test CORS for audio files
curl -H "Origin: https://app.veza.com" \
     -H "Access-Control-Request-Method: GET" \
     -H "Access-Control-Request-Headers: Range" \
     -X OPTIONS \
     https://cdn.veza.com/audio/track-123/song.mp3
```

### Check Cache Status

```bash
# View CDN cache headers
curl -I https://cdn.veza.com/static/css/app.css | grep -i cache
```

## Monitoring

### CDN Metrics

Monitor CDN performance:
- Cache hit ratio
- Origin requests
- Bandwidth usage
- Response times

### Set Up Alerts

Alert on:
- Low cache hit ratio (< 80%)
- High origin requests
- CDN errors

## Best Practices

1. **Use long cache TTLs** for immutable assets (JS, CSS with hashes)
2. **Use shorter TTLs** for dynamic content
3. **Enable compression** (gzip, brotli) at CDN level
4. **Use CDN for audio/video** to reduce origin load
5. **Monitor cache hit rates** and adjust TTLs accordingly
6. **Invalidate cache** when deploying new versions
7. **Use versioned URLs** for assets (e.g., `/static/js/app-v1.2.3.js`)

## Troubleshooting

### Assets Not Loading from CDN

1. Check CDN configuration:
   ```bash
   kubectl get configmap cdn-config -n veza-production -o yaml
   ```

2. Verify CDN base URL is correct
3. Check DNS resolution for CDN domain
4. Verify CORS headers are set correctly

### Cache Not Working

1. Check cache headers in response:
   ```bash
   curl -I https://cdn.veza.com/static/js/app.js
   ```

2. Verify CDN provider settings
3. Check cache TTL configuration
4. Verify CDN is enabled in configmap

### CORS Issues

1. Check CORS headers in nginx config
2. Verify `Access-Control-Allow-Origin` is set
3. Check preflight OPTIONS requests are handled
4. Verify allowed methods and headers

## Additional Resources

- [Cloudflare CDN Documentation](https://developers.cloudflare.com/cache/)
- [AWS CloudFront Documentation](https://docs.aws.amazon.com/cloudfront/)
- [nginx CDN Configuration](https://nginx.org/en/docs/http/ngx_http_headers_module.html)