TokenThrottle

Asynchronously rate-limit by a key. E.g. set thresholds for access to your API by username/token, or IP address.

The default storage is in process memory, but it is easily pluggable by providing a thin wrapper to whatever storage system you would like to use, e.g. Redis for cross-process or cross-machine rate-limiting.

// Create a throttle with 100 access limit per second.
var throttle = require("tokenthrottle")({rate: 100});


// in some_function that you want to rate limit
  throttle.rateLimit(id, function (err, limited) {
    /* ... handle err ... */
    if (limited) {
      return res.next(new Error("Rate limit exceeded, please slow down."));
    }
    else {
      /* ... do work ... */
    }
  })

Wrappers

Convenient wrappers for this library with different storage back-ends:

Redis: tokenthrottle-redis
LevelDb: tokenthrottle-level

Options

There are a number of options available to control how the throttle mechanism works.

rate: {Number} REQUIRED The number of actions to renew during each time window
burst: {Number} A maximum number of actions allowed per time window [default: rate]
window: {Number} The milliseconds in which rate or burst act. [default: 1000]
tokensTable: {TokensTable} A table implementation that supports put(key, object, cb) and get(key, cb)
overrides: {Object} A set of overrides to apply when throttling. e.g.

var throttle = require("tokenthrottle")({
  rate: 100,       // replenish actions at 100 per minute
  burst: 200,      // allow a maximum burst of 200 actions per minute
  window: 60000,   // set the throttle window to a minute
  overrides: {
    "127.0.0.1": {rate: 0}, // No limit for localhost
    "Joe Smith": {rate: 10}, // token "Joe Smith" gets 10 actions per second (Note defaults apply here, does not inherit)
    "2da0f39": {rate: 1000, burst: 2000, window: 1000}, // Allow a lot more actions to this token.
  }
});

Custom Token Table

Here's an example of a custom token table that would use Redis:

(But don't do it manually, use tokenthrottle-redis)

function RedisTable(redisClient) {
  this.client = redisClient;
}
RedisTable.prototype.get = function (key, cb) {
  this.client.hgetall(key, cb);
}
RedisTable.prototype.put = function (key, value, cb) {
  this.client.hmset(key, value, cb);
  // Note: you may want to consider expiring these keys to prevent Redis memory bloat.
}

var throttle = require("tokenthrottle")({
  rate: 100,
  tokensTable: new RedisTable(require("redis").createClient())
})

History

This library is code derived from the original built-in throttle for restify and contains many portions originally written by Mark Cavage. It is actually designed with Restify backward-compatibility in mind for Synchronous in-memory only token-table implementations by wrapping synchronous put/get calls with async versions.

License

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.