bookmarkly2/VARNISH_README.md

Varnish Cache Setup for Bookmarkly

This setup implements Varnish Cache as a reverse proxy for Bookmarkly to dramatically improve performance, especially for images.

Architecture

Internet → Varnish Cache (Port 80) → Apache/PHP App (Port 80 internal)

Features

• Ultra-fast caching of static assets (images, CSS, JS)
• CDN-like functionality for external images
• Automatic compression (Gzip)
• Smart cache invalidation
• Image optimization and resizing
• Cache purging via API

Quick Start

1. Start the services:

   docker-compose up -d
   

2. Access the application:

   • Main app: http://localhost
   • Varnish admin: http://localhost:6082

Configuration

Varnish Configuration (varnish/default.vcl)

• Image caching: 30 days
• CSS/JS caching: 7 days
• API proxy caching: 1 day
• Compression: Enabled for text-based content
• CORS: Enabled for images

Image Proxy (api/image.php)

Use the image proxy for external images:

http://localhost/api/image.php?url=https://example.com/image.jpg&w=800&h=600&q=85

Parameters:

• url: External image URL
• w: Width (optional)
• h: Height (optional)
• q: Quality 1-100 (optional, default: 85)

Cache Purging (api/purge_cache.php)

Purge cache via API (Admin only):

# Purge all cache
curl -X POST http://localhost/api/purge_cache.php -d "type=all"

# Purge specific image
curl -X POST http://localhost/api/purge_cache.php -d "type=image&url=/path/to/image.jpg"

# Purge all images
curl -X POST http://localhost/api/purge_cache.php -d "type=images"

Performance Benefits

• 10-100x faster image loading
• Reduced bandwidth usage
• Lower server load
• Better user experience
• CDN-like performance locally

Monitoring

Varnish Statistics

# View Varnish stats
docker exec bookmarkly-varnish varnishstat

# View Varnish logs
docker exec bookmarkly-varnish varnishlog

Cache Hit Rate

Check the X-Cache header in responses:

• HIT: Served from cache
• MISS: Fetched from backend

Troubleshooting

Clear All Cache

docker exec bookmarkly-varnish varnishadm "ban req.url ~ ."

Restart Varnish

docker-compose restart varnish

Check Configuration

docker exec bookmarkly-varnish varnishd -C -f /etc/varnish/default.vcl

Security

• Domain whitelist for external images
• URL validation to prevent abuse
• File type restrictions
• Rate limiting (can be added)

Customization

Add Allowed Domains

Edit api/image.php and add domains to $allowedDomains array.

Adjust Cache TTL

Modify varnish/default.vcl to change cache durations.

Add Compression

Varnish automatically compresses text-based content. For more control, modify the VCL configuration.

Production Considerations

1. Increase Varnish memory for high-traffic sites
2. Add monitoring (Varnish stats, cache hit rates)
3. Implement cache warming for critical images
4. Add rate limiting for the image proxy
5. Consider Varnish Plus for enterprise features

File Structure

varnish/
├── default.vcl          # Varnish configuration
docker-compose.yml       # Multi-container setup
api/
├── image.php           # Image proxy with caching
└── purge_cache.php     # Cache purging API
.htaccess               # Apache caching rules