fetch-proxy

fetch-proxy

HTTP proxy utilities built on the web Fetch API. Use fetch-proxy to create fetch handlers that forward requests to target servers while optionally rewriting headers and cookies.

Features

• Web Standards - Built on the standard JavaScript Fetch API
• Cookie Rewriting - Supports rewriting Set-Cookie headers received from target server
• Forwarding Headers - Supports X-Forwarded-Proto, X-Forwarded-Host, and X-Forwarded-Port headers
• Encoding Headers - Strips stale encoding and framing headers from proxied responses
• Custom Fetch - Supports custom fetch implementations

Installation

npm i remix

Usage

import { createFetchProxy } from 'remix/fetch-proxy'

// Create a proxy that sends all requests through to remix.run
let proxy = createFetchProxy('https://remix.run')

// This fetch handler is probably running as part of your server somewhere...
function handleFetch(request: Request): Promise<Response> {
  return proxy(request)
}

// Test it out by manually throwing a Request at it
let response = await handleFetch(new Request('https://shopify.com'))

let text = await response.text()
let title = text.match(/<title>([^<]+)<\/title>/)[1]
assert(title.includes('Remix'))

Encoding and Framing Headers

Since proxying is done via fetch rather than raw HTTP messages, some encoding and framing headers need to be removed.

The incoming Accept-Encoding request header describes the final client, so it is not forwarded to the target server.

Since fetch can decompress upstream responses and does not expose raw HTTP transfer framing, fetch-proxy strips response headers that may no longer describe the returned body: Content-Encoding, related Content-Length, and Transfer-Encoding.

To support serving compressed responses to the final client, you'll need to compress the response after the proxy returns it, e.g. with the compressResponse helper from remix/response:

import { createFetchProxy } from 'remix/fetch-proxy'
import { compressResponse } from 'remix/response/compress'

let proxy = createFetchProxy('https://remix.run')

async function handleFetch(request: Request): Promise<Response> {
  let response = await proxy(request)

  return compressResponse(response, request)
}

Related Packages

• node-fetch-server - Build HTTP servers for Node.js using the web fetch API
• response - Create, transform, and compress Fetch API responses

License

See LICENSE