Intermediate LevelWeb Security & Cyber Defense
How do API Gateways enforce distributed rate limiting using Redis sliding window algorithms?
❓ Interview Prompt: Explain distributed rate limiting, API Gateway cluster synchronization, Redis atomic Lua scripts, and handling high-volume request bursts.
Enforcing rate limits across a cluster of multiple API Gateway nodes requires a shared distributed cache (Redis):
Redis Lua Script Execution:
Executing rate limiting checks inside an atomic Redis Lua script guarantees that checking and incrementing counters happen atomically without race conditions between concurrent gateway nodes!
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Headers Returned: Always return 'X-RateLimit-Limit', 'X-RateLimit-Remaining', and 'Retry-After' on '429' responses.
Code Implementation Example
typescript
import { Request, Response } from 'express';
import { redis } from './redis';
export async function distributedRateLimiter(req: Request, res: Response, next: NextFunction) {
const clientIp = req.ip;
const key = 'ratelimit:${clientIp}';
const allowed = await redis.eval(slidingWindowLua, 1, key, Date.now(), 60000, 100);
if (!allowed) {
res.setHeader('Retry-After', 60);
return res.status(429).json({ error: 'Rate limit exceeded' });
}
next();
}💡Distributed rate limiting middleware using atomic Redis Lua scripts.
🎯 Interview Key Takeaway
Enforce distributed rate limiting across API Gateway nodes using atomic Redis Lua scripts.
#Rate Limiting#Redis#API Gateway#Intermediate
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