smart-limiter

Smart rate limiter middleware for both express and koa.

Requirements

Redis 2.8+ with thunk-redis client

Installation

npm install smart-limiter

Example

koa v2

'use strict'

const Koa = require('koa')
const smartLimiter = require('smart-limiter')

const app = new Koa()

app.use(smartLimiter.koav2({
  redis: 6379,
  duration: 10000,
  getId: function (ctx) {
    return ctx.ip
  },
  policy: {
    'GET': [3, 5000],
    'GET /test': [3, 5000, 3, 10000],
    '/test': 5
  }
}))

app.use((ctx) => {
  ctx.body = ctx.headers
})

app.listen(3000)
console.log('Start at 3000')

express

'use strict'

const express = require('express')
const smartLimiter = require('smart-limiter')

const app = express()

app.use(function (req, res, next) {
  if (req.path !== '/favicon.ico') return next()
  res.end()
})

app.use(smartLimiter({
  redis: 6379,
  duration: 10000,
  getId: function (req) {
    return req.ip
  },
  policy: {
    'GET': [3, 5000],
    'GET /test': [3, 5000, 3, 10000],
    '/test': 5
  }
}))

app.use(function (req, res) {
  res.json(res._headers)
})

app.listen(3000)
console.log('Start at 3000')

koa v1

'use strict'

const Koa = require('koa')
const smartLimiter = require('smart-limiter')

const app = new Koa()

app.use(smartLimiter.koa({
  redis: 6379,
  duration: 10000,
  getId: function (ctx) {
    return ctx.ip
  },
  policy: {
    'GET': [3, 5000],
    'GET /test': [3, 5000, 3, 10000],
    '/test': 5
  }
}))

app.use(function * () {
  this.body = this.headers
})

app.listen(3000)
console.log('Start at 3000')

API

var smartLimiter = require('smart-limiter')

smartLimiter(options)

const limiter = smartLimiter({
  redis: thunkRedisClient,
  duration: 10000,
  getId: function (req) {
    return req.ip
  },
  policy: {
    'GET': [3, 5000],
    'GET /test': [3, 5000, 3, 10000],
    '/test': 5
  }
})
app.use(limiter)

return a express middleware.

options.prefix: Optional, Type: String, redis key namespace, default to LIMIT.
options.redis: Optional, {Mix}, thunk-redis instance or thunk-redis options
options.duration: Optional, {Number}, of limit in milliseconds, default to 3600000
options.getId: Required, {Function}, generate a identifier for requests
options.policy: Required, {Object}, limit policy

policy key: It support 3 types: METHOD /path, /path and METHOD. Limiter will try match METHOD /path first, then /path, then METHOD. It means that METHOD /path has highest priority, then fallback to /path and METHOD.

policy value: If value is a member, it means max count with options.duration. If value is array, it should be a pair of max and duration, support one more pairs.

The first pair is default limit policy. If someone touch the maximum of default limit, then the next policy will be apply, and so on. So next policy should be stricter than previous one.

If someone touch the maximum of limit and request again after double current duration time, it will rollback to default policy.

example policy:
```
options.policy = {
  'HEAD': 100,
  'GET': [60, 60000, 30, 60000, 30, 120000],
  'PUT': [40, 60000, 20, 60000, 10, 120000],
  'POST': [40, 60000, 10, 60000],
  'DELETE': [40, 60000, 10, 60000],
  'POST /api/organizations': [10, 60000, 2, 60000],
  'POST /api/projects': [20, 60000, 5, 60000],
  '/api/auth': [10, 60000, 5, 120000],
}
```

limiter.get(id, max, duration, max, duration...) => Promise

Return a promise that guarantee a limiter result. it support more max and duration pairs ad limit policy. The first pairs will be used as default. If some trigger limit, then the limiter will apply the next pair policy.

limiter.remove(req, callback)

limiter.remove(req) => Promise

Remove req's rate limit data. Only available when using express middleware.

limiter.remove(req, function (err, res) {
  console.log(err, res) // null, 1
})

Responses

Example 200 with header fields:

HTTP/1.1 200 OK

Connection:keep-alive
Content-Length:111
Content-Type:application/json; charset=utf-8
Date:Thu, 10 Dec 2015 13:21:55 GMT
X-Powered-By:Express
X-RateLimit-Limit:3
X-RateLimit-Remaining:2
X-RateLimit-Reset:1449753721

Example 429 with header fields:

HTTP/1.1 429 Too Many Requests

Connection:keep-alive
Content-Length:39
Content-Type:text/html; charset=utf-8
Date:Thu, 10 Dec 2015 13:22:36 GMT
Retry-After:3
X-Powered-By:Express
X-RateLimit-Limit:3
X-RateLimit-Remaining:-1
X-RateLimit-Reset:1449753759

teambition/smart-limiter