@destinationstransfers/ratelimiter

ratelimiter

Rate limiter for Node.js backed by Redis.

Release Notes

See CHANGELOG

Requirements

• Redis 2.6.12+ and Node >=7.6

Installation

$ npm install @destinationstransfers/ratelimiter

Example

Example Koa middleware implementation limiting against a user._id:

const Limiter = require('@destinationstransfers/ratelimiter')
const ms = require('ms');
const redis = require('redis');
const db = redis.createClient(...);

const limiter = new Limiter({ db });


...

app.use('*', async (ctx, next) => {
  const limit = await limiter.get(ctx.session.user._id || ctx.ip);

  ctx.set("X-RateLimit-Limit", limit.total);
  ctx.set("X-RateLimit-Remaining", limit.remaining - 1);
  ctx.set("X-RateLimit-Reset", limit.reset);

  // all good
  debug("remaining %s/%s %s", limit.remaining - 1, limit.total, id);
  if (limit.remaining) return next();

  // not good
  const delta = (limit.reset * 1000 - Date.now()) | 0;
  const after = (limit.reset - Date.now() / 1000) | 0;
  ctx.set("Retry-After", after);
  ctx.throw(429, "Rate limit exceeded, retry in " + ms(delta, { long: true }));
})

Result Object

• total - max value
• remaining - number of calls left in current duration without decreasing current get
• reset - time in milliseconds until the end of current duration

Options

Constructor parameters:

• db - redis connection instance
• max - max requests within duration [2500]
• duration - of limit in milliseconds [3600000]

.get parameter:

• id - the identifier to limit against (typically a user id or IP, or token)

License

MIT