Rate Limiting

Enforce rate limits from a worker with the Rate Limiting binding.

The Rate Limiting binding lets a worker check and increment a rate limit counter. The exp/cloudflare/ratelimit package wraps it.

Declare the binding

[[ratelimits]]
name = "MY_RATE_LIMITER"
namespace_id = "1001"
simple = { limit = 100, period = 60 }

namespace_id identifies the counter namespace — bindings that share it, even across different workers, share counters for a given key. simple.period must be 10 or 60 seconds.

Check a key

ratelimit.NewRateLimit resolves the binding by name. Limit increments the counter for RateLimitOptions.Key and returns a RateLimitOutcome whose Success field reports whether the key is under the limit.

import (
	"net/http"

	"github.com/syumai/workers-go"
	"github.com/syumai/workers-go/exp/cloudflare/ratelimit"
)

func main() {
	workers.Serve(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		rl, err := ratelimit.NewRateLimit("MY_RATE_LIMITER")
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		outcome, err := rl.Limit(ratelimit.RateLimitOptions{
			Key: req.RemoteAddr,
		})
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if !outcome.Success {
			http.Error(w, "rate limit exceeded", http.StatusTooManyRequests)
			return
		}
		w.Write([]byte("ok"))
	}))
}