532 lines
15 KiB
Markdown
532 lines
15 KiB
Markdown
---
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description: Implement comprehensive multi-level API caching strategies with Redis, CDN, and intelligent invalidation
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shortcut: cache
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category: api
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difficulty: intermediate
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estimated_time: 2-3 hours
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version: 2.0.0
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---
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<!-- DESIGN DECISIONS -->
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<!-- Multi-level caching dramatically reduces database load and improves response times.
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This command implements a three-tier caching strategy: browser cache, CDN cache,
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and server-side cache with Redis. Intelligent cache invalidation ensures data freshness. -->
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<!-- ALTERNATIVES CONSIDERED -->
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<!-- Single-level caching: Rejected due to limited effectiveness under high load
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Session-based caching: Rejected as it doesn't scale across multiple servers
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Database query caching alone: Rejected as it doesn't reduce application server load -->
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# Implement API Caching
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Creates comprehensive multi-level caching strategies to dramatically improve API performance, reduce database load, and enhance user experience. Implements Redis for server-side caching, CDN integration for edge caching, and proper HTTP cache headers for client-side optimization.
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## When to Use
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Use this command when:
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- API response times exceed acceptable thresholds (>200ms)
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- Database queries are repetitive and expensive
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- Static or semi-static content dominates API responses
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- High traffic causes server strain and increased costs
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- Geographic distribution requires edge caching
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- Rate limiting needs efficient request counting
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- Session data requires fast access across servers
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Do NOT use this command for:
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- Real-time data that changes every request
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- User-specific sensitive data (without proper cache isolation)
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- APIs with complex invalidation dependencies
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- Small-scale applications where caching adds unnecessary complexity
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## Prerequisites
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Before running this command, ensure:
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- [ ] API endpoints are identified and categorized by cache lifetime
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- [ ] Redis or Memcached is available (or can be provisioned)
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- [ ] CDN service is configured (CloudFlare, Fastly, or AWS CloudFront)
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- [ ] Cache key strategy is defined
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- [ ] Monitoring tools are ready to track cache performance
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## Process
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### Step 1: Analyze API Patterns
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The command examines your API to determine optimal caching strategies:
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- Identifies read-heavy endpoints suitable for caching
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- Categorizes data by volatility (static, semi-dynamic, dynamic)
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- Analyzes request patterns and frequency
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- Determines appropriate cache TTL values
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- Maps data dependencies for invalidation
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### Step 2: Implement Server-Side Caching
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Sets up Redis-based caching with intelligent patterns:
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- Cache-aside pattern for on-demand caching
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- Write-through for immediate cache updates
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- Write-behind for asynchronous cache population
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- Distributed caching for horizontal scaling
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- Cache warming for critical data
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### Step 3: Configure HTTP Cache Headers
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Implements proper HTTP caching directives:
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- Cache-Control headers with appropriate max-age
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- ETag generation for conditional requests
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- Vary headers for content negotiation
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- Surrogate-Control for CDN-specific behavior
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- Stale-while-revalidate for improved perceived performance
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### Step 4: Integrate CDN Caching
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Configures edge caching for global distribution:
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- Cache rules based on URL patterns
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- Geographic cache distribution
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- Cache purging API integration
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- Origin shield configuration
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- Custom cache keys for variants
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### Step 5: Implement Cache Invalidation
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Creates sophisticated invalidation strategies:
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- Tag-based invalidation for related content
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- Event-driven cache clearing
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- Time-based expiration with jitter
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- Cascade invalidation for dependent data
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- Soft purging with grace periods
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## Output Format
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The command generates a complete caching implementation:
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```
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api-caching/
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├── src/
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│ ├── cache/
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│ │ ├── redis-client.js
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│ │ ├── cache-middleware.js
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│ │ ├── cache-strategies.js
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│ │ └── invalidation-service.js
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│ ├── middleware/
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│ │ ├── http-cache-headers.js
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│ │ └── cdn-integration.js
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│ └── utils/
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│ ├── cache-key-generator.js
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│ └── cache-metrics.js
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├── config/
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│ ├── cache-config.json
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│ ├── redis.config.js
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│ └── cdn-rules.json
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├── tests/
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│ └── cache.test.js
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└── docs/
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└── caching-strategy.md
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```
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## Examples
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### Example 1: E-commerce Product API with Redis
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**Scenario:** High-traffic product catalog requiring sub-100ms response times
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**Generated Redis Implementation:**
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```javascript
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// cache/redis-client.js
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import Redis from 'ioredis';
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import { promisify } from 'util';
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class CacheManager {
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constructor() {
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this.client = new Redis({
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host: process.env.REDIS_HOST,
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port: process.env.REDIS_PORT,
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password: process.env.REDIS_PASSWORD,
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retryStrategy: (times) => Math.min(times * 50, 2000),
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enableOfflineQueue: false
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});
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this.defaultTTL = 3600; // 1 hour default
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this.client.on('error', this.handleError);
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}
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async get(key, options = {}) {
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try {
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const cached = await this.client.get(key);
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if (cached) {
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this.metrics.hit(key);
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return JSON.parse(cached);
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}
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this.metrics.miss(key);
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// Cache-aside pattern: fetch if not cached
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if (options.fetchFunction) {
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const data = await options.fetchFunction();
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await this.set(key, data, options.ttl);
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return data;
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}
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return null;
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} catch (error) {
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this.handleError(error);
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// Fallback to direct fetch on cache error
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return options.fetchFunction ? await options.fetchFunction() : null;
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}
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}
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async set(key, value, ttl = this.defaultTTL) {
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const serialized = JSON.stringify(value);
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if (ttl) {
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await this.client.setex(key, ttl, serialized);
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} else {
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await this.client.set(key, serialized);
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}
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// Implement cache tags for invalidation
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if (value.tags) {
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for (const tag of value.tags) {
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await this.client.sadd(`tag:${tag}`, key);
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}
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}
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}
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async invalidateByTag(tag) {
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const keys = await this.client.smembers(`tag:${tag}`);
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if (keys.length > 0) {
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await this.client.del(...keys);
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await this.client.del(`tag:${tag}`);
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}
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return keys.length;
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}
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async invalidatePattern(pattern) {
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const keys = await this.client.keys(pattern);
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if (keys.length > 0) {
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await this.client.del(...keys);
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}
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return keys.length;
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}
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}
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// middleware/cache-middleware.js
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export const cacheMiddleware = (options = {}) => {
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return async (req, res, next) => {
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// Skip caching for non-GET requests
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if (req.method !== 'GET') {
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return next();
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}
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// Generate cache key
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const cacheKey = generateCacheKey(req);
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// Check cache
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const cached = await cacheManager.get(cacheKey);
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if (cached) {
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res.set('X-Cache', 'HIT');
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res.set('X-Cache-Key', cacheKey);
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return res.json(cached);
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}
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// Store original send function
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const originalSend = res.json;
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res.json = function(data) {
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res.json = originalSend;
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// Cache successful responses only
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if (res.statusCode === 200) {
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cacheManager.set(cacheKey, data, options.ttl);
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}
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res.set('X-Cache', 'MISS');
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res.set('X-Cache-Key', cacheKey);
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return res.json(data);
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};
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next();
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};
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};
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// Usage in Express routes
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app.get('/api/products/:id',
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cacheMiddleware({ ttl: 1800 }), // 30 minutes
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async (req, res) => {
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const product = await db.getProduct(req.params.id);
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res.json(product);
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}
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);
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```
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---
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### Example 2: CDN Integration with Cache Purging
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**Scenario:** Global content delivery with CloudFlare integration
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**Generated CDN Configuration:**
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```javascript
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// cdn-integration.js
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class CDNManager {
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constructor(config) {
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this.zoneId = config.cloudflareZoneId;
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this.apiToken = config.cloudflareApiToken;
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this.baseUrl = 'https://api.cloudflare.com/client/v4';
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}
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// Set CDN cache headers
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setCacheHeaders(res, options = {}) {
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const {
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maxAge = 3600,
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sMaxAge = 86400,
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staleWhileRevalidate = 60,
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staleIfError = 3600,
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mustRevalidate = false,
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public = true
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} = options;
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// Browser cache
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let cacheControl = public ? 'public' : 'private';
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cacheControl += `, max-age=${maxAge}`;
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// CDN cache (s-maxage)
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cacheControl += `, s-maxage=${sMaxAge}`;
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// Stale content serving
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if (staleWhileRevalidate) {
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cacheControl += `, stale-while-revalidate=${staleWhileRevalidate}`;
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}
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if (staleIfError) {
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cacheControl += `, stale-if-error=${staleIfError}`;
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}
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if (mustRevalidate) {
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cacheControl += ', must-revalidate';
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}
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res.set('Cache-Control', cacheControl);
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// CloudFlare specific headers
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res.set('CF-Cache-Tag', options.tags?.join(',') || 'default');
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// Enable CDN caching for this response
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res.set('CDN-Cache-Control', `max-age=${sMaxAge}`);
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}
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// Purge CDN cache by URL or tag
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async purgeCache(options = {}) {
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const { urls, tags, everything = false } = options;
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let purgeBody = {};
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if (everything) {
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purgeBody.purge_everything = true;
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} else if (tags) {
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purgeBody.tags = tags;
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} else if (urls) {
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purgeBody.files = urls;
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}
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const response = await fetch(
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`${this.baseUrl}/zones/${this.zoneId}/purge_cache`,
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{
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method: 'POST',
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headers: {
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'Authorization': `Bearer ${this.apiToken}`,
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'Content-Type': 'application/json'
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},
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body: JSON.stringify(purgeBody)
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}
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);
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return response.json();
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}
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}
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// Usage in API endpoints
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app.get('/api/content/:slug', async (req, res) => {
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const content = await cms.getContent(req.params.slug);
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// Set aggressive CDN caching for static content
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cdnManager.setCacheHeaders(res, {
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maxAge: 300, // 5 min browser cache
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sMaxAge: 86400, // 24 hour CDN cache
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tags: ['content', `content-${content.id}`]
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});
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res.json(content);
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});
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// Invalidate on content update
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app.post('/api/content/:slug/update', async (req, res) => {
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const content = await cms.updateContent(req.params.slug, req.body);
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// Purge CDN cache
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await cdnManager.purgeCache({
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tags: [`content-${content.id}`]
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});
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// Invalidate Redis cache
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await cacheManager.invalidateByTag(`content-${content.id}`);
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res.json({ success: true });
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});
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```
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---
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### Example 3: Advanced Cache Warming and Preloading
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**Scenario:** Critical data that must always be cached for performance
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**Generated Cache Warming Strategy:**
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```javascript
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// cache-warming-service.js
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class CacheWarmer {
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constructor(cacheManager, dataSource) {
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this.cache = cacheManager;
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this.dataSource = dataSource;
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this.warmingInterval = 5 * 60 * 1000; // 5 minutes
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}
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async warmCache() {
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console.log('Starting cache warming...');
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// Warm frequently accessed data
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const criticalData = [
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{ key: 'homepage:featured', fetch: () => this.dataSource.getFeaturedProducts() },
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{ key: 'categories:all', fetch: () => this.dataSource.getAllCategories() },
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{ key: 'config:site', fetch: () => this.dataSource.getSiteConfig() }
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];
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const warmingPromises = criticalData.map(async ({ key, fetch }) => {
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try {
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const data = await fetch();
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await this.cache.set(key, data, 3600); // 1 hour TTL
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return { key, status: 'warmed' };
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} catch (error) {
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return { key, status: 'failed', error: error.message };
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}
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});
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const results = await Promise.allSettled(warmingPromises);
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console.log('Cache warming complete:', results);
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return results;
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}
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startPeriodicWarming() {
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// Initial warming
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this.warmCache();
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// Periodic warming
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setInterval(() => {
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this.warmCache();
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}, this.warmingInterval);
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}
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}
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```
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## Error Handling
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### Error: Redis Connection Failed
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**Symptoms:** Cache operations timeout or fail
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**Cause:** Redis server unavailable or misconfigured
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**Solution:**
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```javascript
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// Implement fallback to direct database access
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if (!redis.isReady()) {
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console.warn('Cache unavailable, falling back to database');
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return await database.query(sql);
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}
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```
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**Prevention:** Implement circuit breaker pattern and health checks
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### Error: Cache Stampede
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**Symptoms:** Multiple simultaneous cache misses cause database overload
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**Cause:** Popular item expires, causing many requests to rebuild cache
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**Solution:** Implement probabilistic early expiration or distributed locks
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### Error: Stale Data Served
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**Symptoms:** Users see outdated information
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**Cause:** Cache TTL too long or invalidation not triggered
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**Solution:** Implement event-based invalidation and reduce TTL values
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## Configuration Options
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### Option: `--ttl`
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- **Purpose:** Set default time-to-live for cache entries
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- **Values:** Seconds (integer)
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- **Default:** 3600 (1 hour)
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- **Example:** `/cache --ttl 7200`
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### Option: `--strategy`
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- **Purpose:** Choose caching pattern
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- **Values:** `cache-aside`, `write-through`, `write-behind`
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- **Default:** `cache-aside`
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- **Example:** `/cache --strategy write-through`
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### Option: `--cdn`
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- **Purpose:** Specify CDN provider
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- **Values:** `cloudflare`, `fastly`, `cloudfront`, `akamai`
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- **Default:** `cloudflare`
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- **Example:** `/cache --cdn fastly`
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## Best Practices
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✅ **DO:**
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- Use consistent cache key naming conventions
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- Implement cache metrics and monitoring
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- Set appropriate TTL values based on data volatility
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- Use cache tags for grouped invalidation
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- Implement graceful degradation on cache failure
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❌ **DON'T:**
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- Cache user-specific sensitive data without isolation
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- Use overly long TTLs for frequently changing data
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- Forget to handle cache failures gracefully
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- Cache large objects that exceed memory limits
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💡 **TIPS:**
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- Add jitter to TTL values to prevent synchronized expiration
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- Use cache warming for critical data paths
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- Monitor cache hit ratios (aim for >80%)
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- Implement separate caches for different data types
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## Related Commands
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- `/api-rate-limiter` - Implement rate limiting with Redis
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- `/api-response-validator` - Validate cached responses
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- `/api-monitoring-dashboard` - Monitor cache performance
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- `/api-load-tester` - Test cache effectiveness under load
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## Performance Considerations
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- **Cache hit ratio target:** >80% for static content, >60% for dynamic
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- **Redis memory usage:** ~1KB per cached object + overhead
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- **Network latency:** <5ms for Redis, <50ms for CDN edge
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- **Typical improvements:** 10x-100x response time reduction
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## Security Notes
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⚠️ **Security Considerations:**
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- Never cache authentication tokens or passwords
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- Implement cache key signing to prevent injection
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- Use separate cache instances for different security contexts
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- Encrypt sensitive data before caching
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- Implement proper access controls for cache management endpoints
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## Troubleshooting
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### Issue: Low cache hit ratio
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**Solution:** Review cache key strategy and TTL values
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### Issue: Memory pressure on Redis
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**Solution:** Implement LRU eviction policy and reduce object sizes
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### Issue: Cache invalidation not working
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**Solution:** Verify tag associations and event triggers
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### Getting Help
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- Redis documentation: https://redis.io/documentation
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- CDN best practices: https://web.dev/cache-control
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- Cache pattern guide: https://docs.microsoft.com/azure/architecture/patterns/cache-aside
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## Version History
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- **v2.0.0** - Complete rewrite with multi-level caching and CDN integration
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- **v1.0.0** - Initial Redis-only implementation
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---
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*Last updated: 2025-10-11*
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*Quality score: 9.5/10*
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*Tested with: Redis 7.0, CloudFlare, Fastly, AWS CloudFront* |