Request metadata (request.cf)

Read Cloudflare edge request metadata — colo, country, ASN, TLS info — from request.cf.

Cloudflare’s edge attaches metadata to every incoming request, exposed on the underlying Fetch API Request as request.cf. The exp/cloudflare/cf package decodes it into a Go struct.

Read from a request

Inside a workers.Serve handler, cf.FromRequest extracts the cf object from the *http.Request and decodes it into an IncomingRequestCFProperties.

import (
	"fmt"
	"net/http"

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

func main() {
	workers.Serve(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		props, err := cf.FromRequest(req)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		fmt.Fprintf(w, "colo=%s country=%s asn=%v tls=%s",
			props.Colo, props.Country, props.ASN, props.TLSVersion)
	}))
}

IncomingRequestCFProperties flattens all of the request.cf fields — Colo, Country, City, Region, Timezone, Latitude, Longitude, ASN, AsOrganization, HTTPProtocol, TLSVersion, TLSCipher, ClientTcpRtt, and more. A few fields with no stable Go shape (BotManagement, HostMetadata, TLSClientAuth) are exposed as raw js.Value.