Express rate-limiter

Rate limiting middleware for Express applications built on redis

npm install express-limiter --save

const express = require('express')
const app = express()
const client = require('redis').createClient()

const limiter = require('express-limiter')(app, client, prefix = 'ratelimit:')

client.connect().catch( error => console.log(error))

/**
 * you may also pass it an Express 4.0 `Router`
 *
 * router = express.Router()
 * limiter = require('express-limiter')(router, client)
 */

limiter({
  path: '/api/action',
  method: 'get',
  lookup: ['connection.remoteAddress'],
  // 150 requests per hour
  total: 150,
  expire: 1000 * 60 * 60
})

app.get('/api/action', function (req, res) {
  res.send(200, 'ok')
})

API options

limiter(options)

• path: String optional route path to the request
• method: String optional http method. accepts get, post, put, delete, and of course Express' all
• lookup: Function|String|Array.<String> value lookup on the request object. Can be a single value, array or function. See examples for common usages
• total: Number allowed number of requests before getting rate limited
• expire: Number amount of time in ms before the rate-limited is reset
• whitelist: function(req) optional param allowing the ability to whitelist. return boolean, true to whitelist, false to passthru to limiter.
• skipHeaders: Boolean whether to skip sending HTTP headers for rate limits ()
• ignoreErrors: Boolean whether errors generated from redis should allow the middleware to call next(). Defaults to false.
• onRateLimited: Function called when a request exceeds the configured rate limit.

Examples

// limit by IP address
limiter({
  ...
  lookup: 'connection.remoteAddress'
  ...
})

// or if you are behind a trusted proxy (like nginx)
limiter({
  lookup: 'headers.x-forwarded-for'
})

// by user (assuming a user is logged in with a valid id)
limiter({
  lookup: 'user.id'
})

// limit your entire app
limiter({
  path: '*',
  method: 'all',
  lookup: 'connection.remoteAddress'
})

// limit users on same IP
limiter({
  path: '*',
  method: 'all',
  lookup: ['user.id', 'connection.remoteAddress']
})

// whitelist user admins
limiter({
  path: '/delete/thing',
  method: 'post',
  lookup: 'user.id',
  whitelist: function (req) {
    return !!req.user.is_admin
  }
})

// skip sending HTTP limit headers
limiter({
  path: '/delete/thing',
  method: 'post',
  lookup: 'user.id',
  whitelist: function (req) {
    return !!req.user.is_admin
  },
  skipHeaders: true
})

// call a custom limit handler
limiter({
  path: '*',
  method: 'all',
  lookup: 'connection.remoteAddress',
  onRateLimited: function (req, res, next) {
    next({ message: 'Rate limit exceeded', status: 429 })
  }
})

// with a function for dynamic-ness
limiter({
  lookup: function(req, res, opts, next) {
    if (validApiKey(req.query.api_key)) {
      opts.lookup = 'query.api_key'
      opts.total = 100
    } else {
      opts.lookup = 'connection.remoteAddress'
      opts.total = 10
    }
    return next()
  }
})

as direct middleware

app.post('/user/update', limiter({ lookup: 'user.id' }), function (req, res) {
  User.find(req.user.id).update(function (err) {
    if (err) next(err)
    else res.send('ok')
  })
})

License MIT

Happy Rate Limiting!