[BUG] Unlimited concurrent connections are opened when using http proxy

[shartte]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

I am using a http-proxy to connect to a private registry.

(By setting https-proxy = http://someproxy:3128 in npmrc).

When running npm ci, I run into "503 too many connection" errors. After investigating, it turns out that the maxsockets option which npm passes to this lib has no effect if a proxy is used. I verified this by setting DEBUG=https-proxy-agent:agent and running npm:ci. I can observe that the library opens 1700+ connections before the first one is closed again.

Expected Behavior

I'd expect the library to respect maxsockets when using a HTTP proxy.

Steps To Reproduce

1. Use any http proxy with a connection limit
2. Run npm ci (or any other large resolve action)
3. Observe the connection limits being exceeded

Environment

• npm: 9.3.1
• Node: v18.13.0
• OS: Windows (this happens on Linux / our CI/CD too)
• platform: Dell Laptop & CI/CD Servers

[shartte]

Some more information:

This used to happen pre NPM 6, but was intermittently fixed in NPM 6. When we tried updating to Node 16 (with the associated NPM update), this started happening again. Since Node 14 (the last version with an old enough NPM where this doesn't happen) is out of support soon, we have to update now, but this issue is causing all of our builds to fail since our corporation uses a privoxy to whitelist URLs from within the build environment. That proxy has a connection limit of about 1000, which our NPM installs exceed easily after upgrading past Node 14.

My current analysis is: make-fetch-happen / pacote except https-proxy-agent to take care of the per-origin connection limit, but that package doesn't implement any limiting.

[wraithgar]

This is a known issue and is being addressed by npm/statusboard#584

[shartte]

Is there any known workaround for this problem?

also: the linked issue doesn't explicitly list respecting the connection limit in the exit criteria :-| (just in the comments)