cdn

name	cdn
description	Content delivery network optimization
license	MIT
compatibility	opencode
metadata	{"audience":"developer, devops-engineer","category":"devops"}

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 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

# 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

// 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