enhance-your-calm v2.0.0

enhance-your-calm

Sliding window rate limiter based on redis lists. It requires ioredis.

Features

• does not over-penalize clients.
• allows multiple intervals for the same key.
• worst case requires 4 O(1) operations (+ 1 EXPIRE) for each key-interval pair.
• uses a single list of numbers that auto-expires for each key-interval pair.
• max memory cost: an int * number of max allowed calls

Installation

yarn add enhance-your-calm

or

npm install enhance-your-calm

Usage

const Redis = require("ioredis");
const redis = new Redis();

const limiter = require("enhance-your-calm")(redis);

// allow 10 calls per 5 minutes.
const canList = () => limiter.check("list", { max: 10, seconds: 300 });

let listCalls = [];
for (let i = 0; i < 3; i++) {
  listCalls.push(canList());
}
Promise.all(listCalls).then(v => console.log(v)); // outputs [true, true, false]

// allow 1 call per minute and 100 per day.
const canCreate = () => limiter.check(
  "create",
  [{ max: 1, seconds: 60 }, { max: 100, seconds: 24 * 3600 }]
);

let createCalls = [];
createCalls.push(canCreate());
createCalls.push(canCreate());
for (let i = 0; i < 100; i++) {
  createCalls.push(delay(canCreate, 61));
}
Promise.all(createCalls).then(v => console.log(v)); // outputs [true, false, true, true, ..., false]

// if you want to know the generated Redis key name you need to provide the name & interval:
limiter.keyname("listusers", 24 * 3600);

Attribution

Lua code was inspired by @luin's StackOverflow answer

Package name was taken from Twitter's 420 HTTP Status text :)

License

MIT