Simple Rate Limiting with Upstash (Redis)

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1import upstash from '@upstash/redis';
2
3const redis = upstash({
4    url: process.env.UPSTASH_REST_URL,
5    token: process.env.UPSTASH_REST_TOKEN,
6});
7
8export const hashKey = (apiKey: string, minute: number) => {
9    return `limits:${apiKey}:${minute}`;
10};
11
12export const checkLimit = async (apiKey: string) => {
13    const minute = new Date().getMinutes();
14    const key = hashKey(apiKey, minute);
15    const currentLimit = await redis.get(key);
16
17    // Test if limit is reached and throw error if it is
18    if (currentLimit.data) {
19        const count = parseInt(currentLimit.data, 10);
20        if (count > 1000) { // 1000 requests per minute
21            console.error('todo, handle overage here');
22        }
23    }
24
25    // Increment the rate limit counter and ensure it expires in 59 min
26    // Note that if the key is not found, it will be created
27    redis.incr(key);
28    redis.expire(key, 59 * 60); // Expire in 59 minutes
29
30    return currentLimit.data ? parseInt(currentLimit.data, 10) : 1;
31};