Express Rate Limiter

What's it?

Typescript Express Rate Limiter implementation. This implementation allows you to define several things like the key to map the requests, an skip function to determine when so skip request from limiter, etc. Further on the readme you can read about the different configurations.

Installation

npm install --save @mgiamberardino/express-rate-limiter

How to use it?

ES6:

import { ExpressRateLimiter } from '@mgiamberardino/express-rate-limiter';
//const { ExpressRateLimiter } = require('@mgiamberardino/express-rate-limiter');

const app = express();
...
const limiter = new ExpressRateLimiter(options);
app.use(limiter);
limiter.start();
...
const app = app.listen( ... );
// If you use graceful shutdown you shuld stop limiter there.
process.on('exit', () => {
    limiter.stop();
});
...

Options

Using typescript you have an interface for the optiones:

import { ExpressRateLimiter, ExpressLimiterOptions } from '@mgiamberardino/express-rate-limiter';

const options:ExpressLimiterOptions = {
    limiterOptions: {
        keyMapper: ...,
        requestLimit: ...,
        timeWindow:...,
    },
    rejectStatusCode: ...,
    rejectMessage: ...,
};
const limiter = ExpressRateLimiter(options);
limiter.start();
app.use(limiter);
...

Limiter Options

Request Limit

limiterOptions: {
    ...
    requestLimit: 250, // The number of calls allowed for the same key previous to start blocking.
    ...
}

Key Mapper

limiterOptions: {
    ...
    keyMapper: (req) => req.session.user, // A function to determine an identifier for the request.
    ...
}

Time Window

limiterOptions: {
    ...
    timeWindow: 1000, // The time window in milliseconds in which the requests will be analyzed.
    ...
}

Skip Function

limiterOptions: {
    ...
    skipFunction: (req) => !req.session.user, // A function to determine if a request should be ignored by the rate limiter.
    ...
}

Reject Status Code

... = {
    ...,
    rejectStatusCode: 429, // Status code to use when rejecting requests
    ...,
}

Reject Message

... = {
    ...,
    rejectMessage: 'Too Many Requests', // Status code to use when rejecting requests
    ...,
}