🐛 BUG: wrangler dev switches Accept-Encoding and request.cf.clientAcceptEncoding

[thomastoye]

Which Cloudflare product(s) does this pertain to?

Workers Runtime

What version(s) of the tool(s) are you using?

3.34.0 (wrangler)

What version of Node are you using?

18.16.1

What operating system and version are you using?

Ubuntu 20.04.6 LTS 5.4.0-173-generic x86_64

Describe the Bug

Observed behavior

Difference between wrangler dev and deployed Cloudflare Worker in request.headers.get('accept-encoding') and request.cf.clientAcceptEncoding.

curl -H 'Accept-Encoding: hello' https://shy-leaf-70f4.***.workers.dev/:

accept: */*
accept-encoding: gzip, br <-------
cf-connecting-ip: ******
cf-ipcountry: BE
cf-ray: *********
cf-visitor: {"scheme":"https"}
connection: Keep-Alive
host: shy-leaf-70f4.***.workers.dev
user-agent: curl/7.86.0
x-forwarded-proto: https
x-real-ip: ******

Client accept encoding: hello <-------

curl -H 'Accept-Encoding: hello' localhost:8787 (wrangler dev):

accept: */*
accept-encoding: hello <-------
host: localhost:8787
user-agent: curl/7.86.0

Client accept encoding: br, gzip, deflate <-------

See https://developers.cloudflare.com/fundamentals/reference/http-request-headers/#accept-encoding

For incoming requests, the value of this header will always be set to accept-encoding: br, gzip. If the client set a different value, such as accept-encoding: deflate, it will be overwritten and the original value will be available in request.cf.clientAcceptEncoding.

The local case is incorrect: The client provided Accept-Encoding: hello, so request.cf.clientAcceptEncoding should be hello and accept-encoding on the headers should be br, gzip or gzip, br as in the documentation.

Expected behavior

curl -H 'Accept-Encoding: hello' https://shy-leaf-70f4.***.workers.dev/:

accept: */*
accept-encoding: gzip, br <-------
cf-connecting-ip: ******
cf-ipcountry: BE
cf-ray: *********
cf-visitor: {"scheme":"https"}
connection: Keep-Alive
host: shy-leaf-70f4.***.workers.dev
user-agent: curl/7.86.0
x-forwarded-proto: https
x-real-ip: ******

Client accept encoding: hello <-------

curl -H 'Accept-Encoding: hello' localhost:8787 (wrangler dev):

accept: */*
accept-encoding: gzip, br <-------
host: localhost:8787
user-agent: curl/7.86.0

Client accept encoding: hello <-------

Steps to reproduce

A minimal working subset of your worker code

export default {
	async fetch(request, env, ctx) {
		return new Response(
			[...request.headers].map(h => h.join(': ')).join('\n') + '\n\n' +
			`Client accept encoding: ${request.cf.clientAcceptEncoding}`,
			{ headers: { 'Content-Type': 'text/plain' } }
		)
	},
};

A minimal working subset of your wrangler.toml

name = "shy-leaf-70f4"
main = "src/index.js"
compatibility_date = "2024-03-12"

Commands used to start your local dev server, including custom env and cli args

wrangler dev and wrangler deploy. Nothing special.

Steps to be performed in the browser, curl commands, or a test we can run that reliably fails (at least a percent of the time)

Please provide a link to a minimal reproduction

No response

Please provide any relevant error logs

No response

[mrbbot]

Hey! 👋 Thanks for raising this. I've put up a PR that should fix this issue (#5409). Would you be able to try out the pre-release (#5409 (comment)) and confirm this fixes things for you?