/tollbooth

Simple middleware to rate-limit HTTP requests.

Primary LanguageGoMIT LicenseMIT

GoDoc license

Tollbooth

This is a generic middleware to rate-limit HTTP requests.

NOTE 1: This library is considered finished.

NOTE 2: Major version changes are backward-incompatible. v2.0.0 streamlines the ugliness of the old API.

Versions

v1.0.0: This version maintains the old API but all the thirdparty modules are moved to their own repo.

v2.x.x: Brand-new API for the sake of code cleanup, thread safety, & auto-expiring data structures.

v3.x.x: Apparently we have been using golang.org/x/time/rate incorrectly. See issue #48. It always limits X number per 1 second. The time duration is not changeable, so it does not make sense to pass TTL to tollbooth.

v4.x.x: Float64 for max requests per second

v5.x.x: go.mod and go.sum

v6.x.x: Replaced go-cache with github.com/go-pkgz/expirable-cache because go-cache leaks goroutines.

v7.x.x: Replaced time/rate with embedded time/rate so that we can support more rate limit headers.

Five Minute Tutorial

package main

import (
    "net/http"

    "github.com/didip/tollbooth/v7"
)

func HelloHandler(w http.ResponseWriter, req *http.Request) {
    w.Write([]byte("Hello, World!"))
}

func main() {
    // Create a request limiter per handler.
    http.Handle("/", tollbooth.LimitFuncHandler(tollbooth.NewLimiter(1, nil), HelloHandler))
    http.ListenAndServe(":12345", nil)
}

Features

  1. Rate-limit by request's remote IP, path, methods, custom headers, & basic auth usernames.

    import (
    "time"

    "github.com/didip/tollbooth/v7"
    "github.com/didip/tollbooth/v7/limiter"
)

lmt := tollbooth.NewLimiter(1, nil)

// or create a limiter with expirable token buckets
// This setting means:
// create a 1 request/second limiter and
// every token bucket in it will expire 1 hour after it was initially set.
lmt = tollbooth.NewLimiter(1, &limiter.ExpirableOptions{DefaultExpirationTTL: time.Hour})

// Configure list of places to look for IP address.
// By default it's: "RemoteAddr", "X-Forwarded-For", "X-Real-IP"
// If your application is behind a proxy, set "X-Forwarded-For" first.
lmt.SetIPLookups([]string{"RemoteAddr", "X-Forwarded-For", "X-Real-IP"})

// Limit only GET and POST requests.
lmt.SetMethods([]string{"GET", "POST"})

// Limit based on basic auth usernames.
// You add them on-load, or later as you handle requests.
lmt.SetBasicAuthUsers([]string{"bob", "jane", "didip", "vip"})
// You can remove them later as well.
lmt.RemoveBasicAuthUsers([]string{"vip"})

// Limit request headers containing certain values.
// You add them on-load, or later as you handle requests.
lmt.SetHeader("X-Access-Token", []string{"abc123", "xyz098"})
// You can remove all entries at once.
lmt.RemoveHeader("X-Access-Token")
// Or remove specific ones.
lmt.RemoveHeaderEntries("X-Access-Token", []string{"limitless-token"})

// By the way, the setters are chainable. Example:
lmt.SetIPLookups([]string{"RemoteAddr", "X-Forwarded-For", "X-Real-IP"}).
    SetMethods([]string{"GET", "POST"}).
    SetBasicAuthUsers([]string{"sansa"}).
    SetBasicAuthUsers([]string{"tyrion"})

  2. Compose your own middleware by using LimitByKeys().

  3. Header entries and basic auth users can expire over time (to conserve memory).

    import "time"

lmt := tollbooth.NewLimiter(1, nil)

// Set a custom expiration TTL for token bucket.
lmt.SetTokenBucketExpirationTTL(time.Hour)

// Set a custom expiration TTL for basic auth users.
lmt.SetBasicAuthExpirationTTL(time.Hour)

// Set a custom expiration TTL for header entries.
lmt.SetHeaderEntryExpirationTTL(time.Hour)

  4. Upon rejection, the following HTTP response headers are available to users:

    • X-Rate-Limit-Limit The maximum request limit.

    • X-Rate-Limit-Duration The rate-limiter duration.

    • X-Rate-Limit-Request-Forwarded-For The rejected request X-Forwarded-For.

    • X-Rate-Limit-Request-Remote-Addr The rejected request RemoteAddr.

    Upon both success and rejection RateLimit headers are sent:

    • RateLimit-Limit The maximum request limit within the time window (1s).

    • RateLimit-Reset The rate-limiter time window duration in seconds (always 1s).

    • RateLimit-Remaining The remaining tokens.

  5. Customize your own message or function when limit is reached.

    lmt := tollbooth.NewLimiter(1, nil)

// Set a custom message.
lmt.SetMessage("You have reached maximum request limit.")

// Set a custom content-type.
lmt.SetMessageContentType("text/plain; charset=utf-8")

// Set a custom function for rejection.
lmt.SetOnLimitReached(func(w http.ResponseWriter, r *http.Request) { fmt.Println("A request was rejected") })

  6. Tollbooth does not require external storage since it uses an algorithm called Token Bucket (Go library: golang.org/x/time/rate).

Other Web Frameworks

Sometimes, other frameworks require a little bit of shim to use Tollbooth. These shims below are contributed by the community, so I make no promises on how well they work. The one I am familiar with are: Chi, Gin, and Negroni.

My other Go libraries

  • ErrStack: A small library to combine errors and also display filename and line number.

  • Stopwatch: A small library to measure latency of things. Useful if you want to report latency data to Graphite.

  • LaborUnion: A dynamic worker pool library.

  • Gomet: Simple HTTP client & server long poll library for Go. Useful for receiving live updates without needing Websocket.

Contributions

Before sending a PR with code changes, please make sure altered code is covered with tests which are passing, and that golangci-lint shows no errors.

To check the linter output, install it and then run golangci-lint run in the root directory of the repository.