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Rate limit made simple, easy, async. Based on ratelimiter.
Install
$ npm install async-ratelimiter --save
Usage
A simple middleware implementation for whatever HTTP server:
'use strict'
const RateLimiter = require('async-ratelimiter')
const { getClientIp } = require('request-ip')
const Redis = require('ioredis')
const rateLimiter = new RateLimiter({
db: new Redis()
})
const apiQuota = async (req, res, next) => {
const clientIp = getClientIp(req)
const limit = await rateLimiter.get({ id: req.clientIp })
if (!res.finished && !res.headersSent) {
res.setHeader('X-Rate-Limit-Limit', limit.total)
res.setHeader('X-Rate-Limit-Remaining', Math.max(0, limit.remaining - 1))
res.setHeader('X-Rate-Limit-Reset', limit.reset)
}
return !limit.remaining
? sendFail({ req,
res,
code: HTTPStatus.TOO_MANY_REQUESTS,
message: MESSAGES.RATE_LIMIT_EXCEDEED()
})
: next(req, res)
}
API
constructor(options)
It creates an rate limiter instance.
options
db
Required
Type: object
The redis connection instance.
max
Type: number
Default: 2500
The maximum number of requests within duration.
duration
Type: number
Default: 3600000
How long keep records of requests in milliseconds.
namespace
Type: string
Default: 'limit'
The prefix used for compound the key.
id
Type: string
The identifier to limit against (typically a user id).
You can pass this value using when you use .get method as well.
.get(options)
Given an id, returns a Promise with the status of the limit with the following structure:
total:maxvalue.remaining: number of calls left in currentdurationwithout decreasing currentget.reset: time since epoch in seconds that the rate limiting period will end (or already ended).
options
id
Type: string
Default: this.id
The identifier to limit against (typically a user id).
max
Type: number
Default: this.max
The maximum number of requests within duration. If provided, it overrides the default max value. This is useful for custom limits that differ between IDs.
duration
Type: number
Default: this.max
How long keep records of requests in milliseconds. If provided, it overrides the default duration value.
decrease
Type: boolean
Default: true
When set to false, the remaining number of calls is not decreased.
In some scenarios it might be useful to be able to read the current "remaining" value for a limiter.
const loginHandler = async (req, res, next) => {
const clientIp = getClientIp(req)
const limit = await rateLimiter.get({ id: clientIp, decrease: false })
if (!limit.remaining) return sendError(req, res, 429)
try {
await doLogin(req)
} catch (err) {
if (err) {
await rateLimiter.get({ id: req.clientIp })
return sendError(req, res, 401)
}
}
next(req, res)
}
In this example, new login attempts are rejected when more at least 10 unsuccessful login attempts happened in the last 60 seconds.
Related
- express-slow-down – Slow down repeated requests; use as an alternative (or addition) to express-rate-limit.
License
async-ratelimiter © microlink.io, released under the MIT License.
Authored and maintained by microlink.io with help from contributors.
microlink.io · GitHub microlink.io · Twitter @microlinkhq