Distributed Rate Limiter

A distributed rate limiter library using Redis.

Introduction

This package provides a rate limiter that uses Redis for distributed locking and storage. It is designed to work in a distributed environment with multiple Node.js servers.

The rate limiter uses a token bucket algorithm to control the rate of requests. It maintains a token bucket for each unique ID that is passed to the execute() method. The bucket is initialized with a specified number of tokens and a duration, which determines the rate at which tokens are replenished. Each time the execute() method is called with a unique ID, the rate limiter checks the token bucket for that ID and determines whether the request should be allowed based on the number of tokens available in the bucket.

Installation

To install the package, use the following command:

npm install distrate

Usage

To use the package, create an instance of the DistRate class and call the execute() method with a unique ID for each request. The method returns a boolean indicating whether the request should be allowed or not.

import IORedis from "ioredis";
import { DistRate } from "distrate";

const redisClient = new IORedis.Cluster([...]);

const rateLimiter = new DistRate({
  tokens: 10,
  duration: 60,
  redisClient,
});

const allowed = await rateLimiter.execute("user123");

Options

The DistRate constructor takes an options object with the following properties:

• tokens (required): The number of tokens in the token bucket.
• duration (required): The duration in seconds for which the tokens are replenished.
• redisClient (required): An instance of the ioredis client to use for distributed locking and storage.
• lockRetryCount (optional): The maximum number of times to retry acquiring the Redis lock when executing the rate limiter (default: 5).
• maxBackoffDelay (optional): The maximum delay in milliseconds between retries when acquiring the Redis lock (default: 5000).
• initialBackoffDelay (optional): The initial delay in milliseconds between retries when acquiring the Redis lock (default: 50).
• backoffMultiplier (optional): The factor by which to increase the delay between retries when acquiring the Redis lock (default: 1.5).
• redisKeyTimeout (optional): The timeout in milliseconds for the Redis key lock (default: 5000).
• enableAnalytics (optional): A boolean indicating whether to enable analytics logging (default: false).

License: MIT