`fetch` support for HTTP/2 by default about undici HOT 12 OPEN

HTTP/2 support in undici is experimental and not enabled by default. Note that we do not support H2, but only HTTP/2 (over TLS), due the necessary protocol selection.

To enable:

import { createServer, constants } from 'node:http2';
import { once } from 'node:events';
import { setGlobalDispatcher, Agent } from './index.js';

const {
  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_CONTENT_TYPE,
} = constants;

setGlobalDispatcher(new Agent({
  allowH2: true
}));

fetch('https://api.sandbox.push.apple.com').then(r => r.text()).then(console.log)

I think we could enable it in the next major and see how it goes. Unfortunately it might be breaking in case of bugs.

from undici.

I believe it should be fine as soon as we keep it as experimental though enabled by default when chosen by the server.

Good Idea! Repeating it for everybody:

We want to enable HTTP/2 if it is the only protocol that the server advertises in the TLS exchange, but prefer HTTP/1.1 for everything else. 100% agreed.PR?

from undici.

Duplicate of #399. AFAICT it has already been implemented.

from undici.

@aduh95 Can you elaborate? Does nodeJs use undici? If yes, in what version is this supported? I'm using Node 20, which is latest LTE version and fetch there doesn't support H2.

from undici.

Does nodeJs use undici?

Correct (it is also maintained by us) https://github.com/nodejs/node/blob/109ab0a89cdeff5717a2a16edd27bafecc104cf6/doc/contributing/maintaining/maintaining-http.md#L54-L56

You can check what version of Undici your build is using in process.versions.undici.

I'm using Node 20, which is latest LTE version and fetch there doesn't support H2.

Any chance you could send a repro? So we can reopen this issue and transfer it to the Undici repo.

from undici.

I don't know much about HTTP/2, but here's an example that works in a browser (do it from the website itself to avoid CORS issue), while it fails in Node.js:

fetch('https://api.sandbox.push.apple.com').then(r => r.text()).then(console.log)

It's not easy to find a public URL that only works with HTTP/2.

from undici.

Created a minimal repro:

import { createServer, constants } from 'node:http2';
import { once } from 'node:events';

const {
  HTTP2_HEADER_STATUS,
  HTTP2_HEADER_CONTENT_TYPE,
} = constants;

const server = createServer();

server.on('stream', (stream, headers) => {
  stream.respond({
    [HTTP2_HEADER_STATUS]: 200,
    [HTTP2_HEADER_CONTENT_TYPE]: 'text/plain; charset=utf-8',
    'Access-Control-Allow-Origin': '*',
  });
  stream.write('hello world');
  stream.end();
});


server.listen(3000);
await once(server, 'listening');

const response = await fetch('http://localhost:3000/');

console.assert(response.ok, response.status);
console.log(await response.text());

server.close();

I can confirm the above code works with Deno and fails with the latest main.

from undici.

I believe it should be fine as soon as we keep it as experimental though enabled by default when chosen by the server.

from undici.

@mcolina Just to clraify: I'm using Http2SecureServer with allowHttp1: true to return an error on unexpectedProtocol. So sounds like my server would always return the error in this proposal.

Can this behavior be controlled by a flag?!

from undici.

@mctrafik you can already turn on http2 with:

import { setGlobalDispatcher, Agent } from 'undici';

setGlobalDispatcher(new Agent({
  allowH2: true
}));

from undici.

I believe it should be fine as soon as we keep it as experimental though enabled by default when chosen by the server.

Good Idea! Repeating it for everybody:

We want to enable HTTP/2 if it is the only protocol that the server advertises in the TLS exchange, but prefer HTTP/1.1 for everything else. 100% agreed.PR?

SGTM 👍

from undici.

If anyone is looking for a way to enable H2 without requiring undici (which is currently not exposed as a node built-in), here's the trick:

global[Symbol.for("undici.globalDispatcher.1")] = new global[Symbol.for("undici.globalDispatcher.1")].constructor({
	allowH2: true,
});

Cheers

from undici.