Wrangler: [dev] Different behavior of "Accept-Encoding" header

Created on 30 Jun 2020 · 4Comments · Source: cloudflare/wrangler

Original mentioned here as feedback for the dev mode.

request.headers.get('Accept-Encoding');

Currently the wrangler dev runtime has different behavior for the Accept-Encoding header than a cloud deployed worker. Accessing it returns the actual values of a client (e.g. gzip, deflate, br) which can be misleading as later on those won't be forwarded but always replaced with gzip. Having them aligned helps to be consistent so developers can be aware of that circumstance before running the worker in production.

status - PR attached user report wontfix

Source

autarc

Most helpful comment

ok - from my investigation when sending Accept-Encoding: gzip, deflate, br as a request header

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) { 
  let accept_encoding = request.headers.get("Accept-Encoding")
  console.log(accept_encoding)
  let response = await fetch("https://example.com")
  let content_encoding = response.headers.get("Content-Encoding")
  console.log(content_encoding)
  return response
}

|command|console.log(accept_encoding)|console.log(content_encoding)|observed Content-Encoding response header|
|---|---|---|---|
|wrangler dev|gzip, deflate, br|null|Header does not exist|
|wrangler preview|gzip, deflate, br|null|Header does not exist|
|wrangler publish|gzip|null|br|

EverlastingBugstopper on 30 Jun 2020

👍2

All 4 comments

ok - from my investigation when sending Accept-Encoding: gzip, deflate, br as a request header

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) { 
  let accept_encoding = request.headers.get("Accept-Encoding")
  console.log(accept_encoding)
  let response = await fetch("https://example.com")
  let content_encoding = response.headers.get("Content-Encoding")
  console.log(content_encoding)
  return response
}

EverlastingBugstopper on 30 Jun 2020

👍2

This will be fixed when we release the stuff in #1085 - i just built wrangler dev from branch avery/edge-dev-server and i get the following:

|command|console.log(accept_encoding)|console.log(content_encoding)|observed Content-Encoding response header|
|---|---|---|---|
|wrangler dev|gzip|null|br|

this is the same you see when you publish a worker 😄

edit: for context, wrangler dev is not actually offline, it connects to a preview service running the workers runtime in GCP. our next upgrade to wrangler dev makes those requests go through Cloudflare's edge network instead of GCP, which will give a much more accurate depiction of what's going to happen when you push to production.

EverlastingBugstopper on 30 Jun 2020

🎉1

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