cdn

## What I do - Design and implement CDN architectures for global content delivery - Optimize cache strategies and invalidation policies - Configure origin shielding and multi-CDN setups - Implement edge computing logic at CDN locations - Secure CDN endpoints against attacks - Analyze CDN performance and optimize delivery ## When to use me - When serving static assets to global audiences - When reducing latency for geographically distributed users - When protecting origin servers from traffic spikes - When implementing DDoS protection and WAF - When you need video streaming or large file delivery - When optimizing costs for high-traffic applications ## Key Concepts ### Cache Configuration ```nginx # Nginx CDN configuration location /static/ { # Cache for 1 year for versioned assets expires 1y; add_header Cache-Control "public, immutable"; # Enable CDN caching proxy_cache_valid 200 60m; proxy_cache_use_stale error timeout http_500; # Set cache key proxy_cache_key "$scheme$request_method$host$request_uri"; } location /api/ { # Don't cache API responses by default proxy_cache_bypass $http_cache_control; add_header Cache-Control "no-store"; } ``` ### CDN Provider Comparison | Provider | Strengths | Use Cases | |----------|----------|-----------| | CloudFlare | DDoS protection, Workers | Security-focused, edge compute | | AWS CloudFront | AWS integration, Lambda@Edge | AWS ecosystems | | Fastly | Real-time purging, VCL | Custom caching, streaming | | Akamai | Global reach, enterprise | Large-scale, video | | Google Cloud CDN | GCP integration | GCP ecosystems | ### Cache Invalidation ```bash # CloudFront invalidation aws cloudfront create-invalidation \ --distribution-id $DIST_ID \ --paths "/static/*" "/images/*" # CloudFlare purge curl -X POST "https://api.cloudflare.com/client/v4/zones/$ZONE/purge_cache" \ -H "Authorization: Bearer $TOKEN" \ -H "Content-Type: application/json" \ --data '{"purge_everything": true}' ``` ### Edge Computing ```javascript // Cloudflare Worker example addEventListener('fetch', event => { event.respondWith(handleRequest(event.request)) }) async function handleRequest(request) { const url = new URL(request.url) // A/B testing at the edge const variant = Math.random() < 0.5 ? 'a' : 'b' const response = await fetch(request) // Add variant header const newResponse = new Response(response.body, response) newResponse.headers.set('X-Variant', variant) return newResponse } ``` ### Performance Optimization - Enable HTTP/2 or HTTP/3 for multiplexing - Use compression (gzip, brotli) - Implement image optimization at edge - Enable HTTP secure headers - Configure proper cache-control headers - Use signed URLs for private content