CDN & Edge Caching

1// ============================================
2// CDN & Edge Caching — Implementation
3// ============================================
4
5const express = require('express');
6const app = express();
7
8// Static assets: immutable, cache forever
9app.get('/static/:hash/:file', (req, res) => {
10  res.set('Cache-Control', 'public, max-age=31536000, immutable');
11  res.sendFile(`/static/\${req.params.hash}/\${req.params.file}`);
12});
13
14// API: CDN caches 60s, browser always revalidates
15app.get('/api/products', (req, res) => {
16  res.set({
17    'Cache-Control': 'public, s-maxage=60, max-age=0, stale-while-revalidate=30',
18    'Vary': 'Accept-Encoding',
19  });
20  res.json({ products: [] });
21});
22
23// Private: Never cache on CDN
24app.get('/api/me/profile', (req, res) => {
25  res.set('Cache-Control', 'private, no-store');
26  res.json({ user: req.user });
27});
28
29// ---------- CDN Purge API ----------
30class CDNManager {
31  async purgeUrls(urls) {
32    console.log(`Purging \${urls.length} URLs from CDN`);
33    // Call CDN provider API (Cloudflare, CloudFront, etc.)
34  }
35
36  async purgeByTag(tags) {
37    console.log(`Purging tags: \${tags.join(', ')}`);
38  }
39}
40
41// ---------- Versioned Static Assets ----------
42const crypto = require('crypto');
43const fs = require('fs');
44
45function getAssetUrl(filePath) {
46  const content = fs.readFileSync(filePath);
47  const hash = crypto.createHash('md5').update(content).digest('hex').slice(0, 8);
48  const ext = filePath.split('.').pop();
49  const basename = filePath.split('/').pop().replace(`.\${ext}`, '');
50  return `/static/\${basename}.\${hash}.\${ext}`;
51}
52
53console.log("CDN patterns configured.");