undici 8 update

[mcollina]

In the upcoming Node.js v26, the @nodejs/undici team would like to ship undici 8, which includes some breaking change refactorings and dropping support for Node 20.

I hoped I could ship it this week, but I'm likely running late for the cutoff

cc @nodejs/releasers

Ref: nodejs/undici#4916
Ref: #61832

[panva]

Undici stores this dispatcher under Symbol.for('undici.globalDispatcher.2')

Am I right to suspect this might be a headache?

[mcollina]

Am I right to suspect this might be a headache?

Mostly for the undici team, hopefully not for users.
It would mean that to support 22, 24 and 26 you'd need to use Undici 8.

Hopefully not, this is handled correctly in Undici 8.

[panva]

Will a package using undici 8 as a dependency used to build a dispatcher passed to globalThis.fetch() work across 22, 24, and 26? e.g.

dispatcher ??= new undici.Agent({
  connect(opts, cb) {
    undici.buildConnector({})(opts, (err, socket) => {
      if (err) {
        cb(err);
      } else if (isSpecialUseIP(socket.remoteAddress)) {
        socket.destroy();
        cb(new Error('hostname resolves to a special-use IP address'));
      } else {
        cb(null, socket);
      }
    });
  },
});
options.dispatcher = dispatcher;

[mcollina]

setGlobalDispatcher() would set it globally correctly, and there is an adapter for "old nodes". If better compact is needed, I think we can figure it out.

[hildjj]

I'm using the undici.globalDispatcher.1 symbol to extract the Agent class from inside node in dohdec, but I would be happy to try one and then the other, or to use the node version to work around this.

Even better would be for node to expose the Agent class so I don't have to perform this ugly hack. :)