httprate

net/http request rate limiter based on the Sliding Window Counter pattern inspired by CloudFlare https://blog.cloudflare.com/counting-things-a-lot-of-different-things/.

The sliding window counter pattern is accurate, smooths traffic and offers a simple counter design to share a rate-limit among a cluster of servers. For example, if you'd like to use redis to coordinate a rate-limit across a group of microservices you just need to implement the httprate.LimitCounter interface to support an atomic increment and get.

Example

package main

import (
  "net/http"

  "github.com/go-chi/chi/v5"
  "github.com/go-chi/chi/v5/middleware"
  "github.com/go-chi/httprate"
)

func main() {
  r := chi.NewRouter()
  r.Use(middleware.Logger)

  // Enable httprate request limiter of 100 requests per minute.
  //
  // In the code example below, rate-limiting is bound to the request IP address
  // via the LimitByIP middleware handler.
  //
  // To have a single rate-limiter for all requests, use httprate.LimitAll(..).
  //
  // Please see _example/main.go for other more, or read the library code.
  r.Use(httprate.LimitByIP(100, 1*time.Minute))

  r.Get("/", func(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("."))
  })

  http.ListenAndServe(":3333", r)
}

Common use cases

Rate limit by IP and URL path (aka endpoint)

  r.Use(httprate.Limit(
  	10,             // requests
  	10*time.Second, // per duration
  	httprate.WithKeyFuncs(httprate.KeyByIP, httprate.KeyByEndpoint),
  ))

Rate limit by arbitrary keys

  r.Use(httprate.Limit(
    100,           // requests
    1*time.Minute, // per duration
    // an oversimplified example of rate limiting by a custom header
    httprate.WithKeyFuncs(func(r *http.Request) (string, error) {
    	return r.Header.Get("X-Access-Token"), nil
    }),
  ))

Send specific response for rate limited requests

  r.Use(httprate.Limit(
    10,            // requests
    1*time.Second, // per duration
    httprate.WithLimitHandler(func(w http.ResponseWriter, r *http.Request) {
      http.Error(w, "some specific response here", http.StatusTooManyRequests)
    }),
  ))

Related packages

Redis backend for httprate: https://github.com/go-chi/httprate-redis

LICENSE

MIT

bendrucker/httprate