Expose Undici's ProxyAgent and setGlobalDispatcher within Node

@pimterry

Originally posted by @pimterry in #42814 (comment)

As a motivating example: I'd love to automatically support global Fetch in https://www.npmjs.com/package/global-agent (drop-in lib to make all Node HTTP use the system proxy) but even though Node bundles Undici AFAICT this isn't possible without adding a full separate Undici dep to that lib, which would more than double its size, ~~just~~ [EDIT: largely] to ship code that's already present in Node itself.

This would be immediately solved if ProxyAgent and setGlobalDispatcher were exposed explicitly somewhere in future.

I've just done a quick test on main in Undici: exposing ProxyAgent & setGlobalDispatcher explicitly increases the Undici bundle size from 334.2kb to 336.0kb (+1.8kb / +0.5%).

Could these APIs be included and exposed in future? Agents for HTTP are a very core API that it would be useful to have usable out of the box, the equivalent functionality is usable OOTB for the legacy http module APIs, and 2kb is not a significant jump in bundle size for this functionality.

setGlobalDispatcher is exposed:

global[Symbol.for('undici.globalDispatcher.1')] = yourDispatcher;

@mcollina

Replying to the last comment from @mcollina in the previous issue:

I would recommend opening up a separate issue about this topic and bringing it to the TSC. I don't think the whole of Undici has the stability guarantees needed to be part of the Node.js LTS cycle yet.

This makes sense! I'm not aware of Undici's process around stability guarantees like this, but I can understand how there are constraints there.

I do understand this isn't a top top priority since installing & importing Undici elsewhere is a usable workaround, so there's certainly no rush just would justify shipping an unstable API unnecessarily. I do think that the current situation isn't a good end state though, and there are good options we can aim for to fix this, so it would be great to find agreement to aim in that direction in the medium term.

I'm not sure how to take anything to the TSC, but very happy to be included on any discussion of this any time.

global[Symbol.for('undici.globalDispatcher.1')] = yourDispatcher;

That's does work as a workaround, but it's not especially nice as the official API for this, and I think ProxyAgent needs to be available too to make this usable for global Fetch.

I don't think we should expose undici further until we want to consider fetch as stable.

@mcollina

@mcollina
I don't think we should expose undici further until we want to consider fetch as stable.

2022-11-14, Version 19.1.0

drop fetch experimental warning (Matteo Collina) lib: drop fetch experimental warning #45287

That does not mark it stable, on purpose. It's the first step on that journey. This is something we might want to consider right now.

In the TSC meeeting of today, we decided that we are going to support HTTP_PROXY, HTTPS_PROXY and NO_PROXY env variables directly in Undici: nodejs/undici#1650.

How is it going to handle different casing rules?

feat: support https_proxy

feat: support https_proxy (#1)

setGlobalDispatcher is exposed:
global[Symbol.for('undici.globalDispatcher.1')] = yourDispatcher;

Is there a workaround to obtain ProxyAgent?

Bring in undici to support proxied fetch

@mcollina

@mcollina is exposing some undici internals still in the plan? Couldn't find the tracking issue from the last collab summit

Is there currently any workaround to set proxy settings for specific requests that doesn't involve adding a dependency on undici?

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Would http.setGlobalProxyFromEnv([env]) solve this issue?

@hyrious

@hyrious that doesn't solve my use case, because I need to use a proxy for some requests, but not all of them, so I can't set proxy settings globally.

@tmccombs

@tmccombs I see. I just searched for the implementation of fetch dispatcher and found that the dispatcher was captured instantly on calling fetch, so in theory there's a hacky way to make proxy happen per fetch without adding a new dependency:

async function fetchWithTemporaryGlobalProxy(url, init, proxyEnv) {
  const restore = setGlobalProxyFromEnv(proxyEnv);

  try {
    return fetch(url, init);
  } finally {
    restore();
  }
}

This is bound to the implementation so not that stable.

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It will be automatically closed in 30 days if no further activity occurs. If this is still relevant, please leave a comment or update it to keep it open.

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Expose Undici's ProxyAgent and setGlobalDispatcher within Node #43187

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Expose Undici's ProxyAgent and setGlobalDispatcher within Node #43187

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targos commented on May 23, 2022

pimterry commented on May 23, 2022

pimterry commented on May 23, 2022

mcollina commented on May 23, 2022

frank-dspeed commented on May 24, 2022

mcollina commented on May 24, 2022

sosoba commented on Dec 5, 2022

mcollina commented on Dec 5, 2022

mcollina commented on Jan 18, 2023

GabenGar commented on Jan 18, 2023

JasonKleban commented on Nov 15, 2023

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metcoder95 commented on Oct 31, 2025

tmccombs commented on Nov 19, 2025

github-actions commented on Jun 25, 2026

hyrious commented on Jun 25, 2026

tmccombs commented on Jun 25, 2026

hyrious commented on Jun 25, 2026

thw0rted commented on Jun 29, 2026

github-actions commented on Sep 28, 2026

mbrevda commented on Sep 28, 2026

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