auth0 / limitd-redis

The database for limitd.

limitd-redis is client for limits on top of redis using Token Buckets. It's a fork from LimitDB.

Installation

npm i limitd-redis

Configure

Create an instance of limitd-redis as follows:

const Limitd = require('limitd-redis');

const limitd = new Limitd({
  uri: 'localhost',
  //or
  nodes: [{
    port: 7000,
    host: 'localhost'
  }],
  buckets: {
    ip: {
      size: 10,
      per_second: 5
    }
  },
  prefix: 'test:',
  ping: {
    interval: 1000,
    maxFailedAttempts: 5,
    reconnectIfFailed: true
  }
});

Options available:

• uri (string): Redis Connection String.
• nodes (array): Redis Cluster Configuration.
• buckets (object): Setup your bucket types.
• prefix (string): Prefix keys in Redis.
• ping (object): Configure ping to Redis DB.

Buckets:

• size (number): is the maximum content of the bucket. This is the maximum burst you allow.
• per_interval (number): is the amount of tokens that the bucket receive on every interval.
• interval (number): defines the interval in milliseconds.
• unlimited (boolean = false): unlimited requests (skip take).
• skip_n_calls (number): take will go to redis every n calls instead of going in every take.

Ping:

• interval (number): represents the time between two consecutive pings. Default: 3000.
• maxFailedAttempts (number): is the allowed number of failed pings before declaring the connection as dead. Default: 5.
• reconnectIfFailed (boolean): indicates whether we should try to reconnect is the connection is declared dead. Default: true.

You can also define your rates using per_second, per_minute, per_hour, per_day. So per_second: 1 is equivalent to per_interval: 1, interval: 1000.

If you omit size, limitdb assumes that size is the value of per_interval. So size: 10, per_second: 10 is the same than per_second: 10.

If you don't specify a filling rate with per_interval or any other per_x, the bucket is fixed and you have to manually reset it using PUT.

You can also define overrides inside your type definitions as follows:

buckets = {
  ip: {
    size: 10,
    per_second: 5,
    overrides: {
      '127.0.0.1': {
        size: 100,
        per_second: 50
      }
    }
  }
}

In this case the specific bucket for 127.0.0.1 of type ip will have a greater limit.

It is also possible to define overrides by regex:

overrides: {
  'local-ips': {
    match:      /192\.168\./
    size:       100,
    per_second: 50
  }
}

It's possible to configure expiration of overrides:

overrides: {
  '54.32.12.31': {
    size:       100,
    per_second: 50,
    until:      new Date(2016, 4, 1)
  }
}

Breaking changes from Limitdb

• Elements will have a default TTL of a week unless specified otherwise.

TAKE

limitd.take(type, key, [count], (err, result) => {
  console.log(result);
});

limitd.take takes the following arguments:

• type: the bucket type.
• key: the identifier of the bucket.
• count: the amount of tokens you need. This is optional and the default is 1.
• configOverride: caller-provided bucket configuration for this operation

The result object has:

• conformant (boolean): true if the requested amount is conformant to the limit.
• remaining (int): the amount of remaining tokens in the bucket.
• reset (int / unix timestamp): unix timestamp of the date when the bucket will be full again.
• limit (int): the size of the bucket.

PUT

You can manually reset a fill a bucket using PUT:

limitd.put(type, key, [count], (err, result) => {
  console.log(result);
});

limitd.put takes the following arguments:

• type: the bucket type.
• key: the identifier of the bucket.
• count: the amount of tokens you want to put in the bucket. This is optional and the default is the size of the bucket.
• configOverride: caller-provided bucket configuration for this operation

Overriding Configuration at Runtime

Since the method of storing overrides for buckets in memory does not scale to a large number, limitd-redis provides a way for callers to pass in configuration from an external data store. The shape of this configOverride parameter (available on take, put, get, and wait) is exactly the same as Buckets above ^.

An example configuration override call might look like this:

const configOverride = {
  size: 45,
  per_hour: 15
}
// take one
limitd.take(type, key, { configOverride }, (err, result) => {
  console.log(result);
}
// take multiple
limitd.take(type, key, { count: 3, configOverride }, (err, result) => {
  console.log(result);
}););

Config overrides follow the same rules as Bucket configuration elements with respect to default size when not provided and ttl.

Author

Auth0

License

This project is licensed under the MIT license. See the LICENSE file for more info.