Cannot use corepack in offline mode

[Qwarctick]

Hello,

I'm trying to use corepack in full offline mode. I got an error when running yarn where corepack try to fetch data from yarnpkg or npmjs.org even if I set the variable COREPACK_ENABLE_NETWORK=0.

I created this test case with a container without internet access after installation of corepack/yarn.

package.json

{
  "name": "js-analysis",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "devDependencies": {
    "jest": "^29.7.0",
    "jest-serializer-vue": "^3.1.0"
  }
}

Dockerfile

FROM node:slim

COPY package.json /src/package.json

WORKDIR /src

RUN corepack enable \
  && corepack yarn@4.x install

ENV COREPACK_ENABLE_NETWORK=0

docker network create --internal --driver bridge no-internet
docker build -f Dockerfile -t js-analysis:latest .

docker run -it --rm --network no-internet js-analysis:latest bash

root@436cdc8b9722:/src# yarn
/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21521
    throw new UsageError(`Network access disabled by the environment; can't reach npm repository ${npmRegistryUrl}`);
          ^

UsageError: Network access disabled by the environment; can't reach npm repository https://registry.npmjs.org
    at fetchAsJson2 (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21521:11)
    at fetchLatestStableVersion (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21550:26)
    at fetchLatestStableVersion2 (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21672:20)
    at Engine.getDefaultVersion (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:22292:29)
    at async Engine.executePackageManagerRequest (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:22390:47)
    at async Object.runMain (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:23096:5) {
  clipanion: { type: 'usage' }
}

Node.js v22.8.0

[aduh95]

Consider setting DEBUG=corepack in your env to better understand what's happening.

[Qwarctick]

root@ddd6d989a9e8:/src# export DEBUG=corepack
root@ddd6d989a9e8:/src# yarn
  corepack LastKnownGood file would be located at /root/.cache/node/corepack/lastKnownGood.json +0ms
  corepack No LastKnownGood version found in Corepack home. +4ms
/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21521
    throw new UsageError(`Network access disabled by the environment; can't reach npm repository ${npmRegistryUrl}`);
          ^

UsageError: Network access disabled by the environment; can't reach npm repository https://registry.npmjs.org
    at fetchAsJson2 (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21521:11)
    at fetchLatestStableVersion (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21550:26)
    at fetchLatestStableVersion2 (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:21672:20)
    at Engine.getDefaultVersion (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:22292:29)
    at async Engine.executePackageManagerRequest (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:22390:47)
    at async Object.runMain (/usr/local/lib/node_modules/corepack/dist/lib/corepack.cjs:23096:5) {
  clipanion: { type: 'usage' }
}

Node.js v22.8.0

[aduh95]

No LastKnownGood version found

That seems to be the issue. If you run corepack install -g yarn@4.x might solve that (I'm just guessing, I'm not using Docker).

where corepack try to fetch data from yarnpkg or npmjs.org even if I set the variable COREPACK_ENABLE_NETWORK=0

To clarify, I don't think that's what happens. When network is disabled by env, Corepack won't even try to fetch anything – and instead throw the error you're seeing. If you actually see some connection attempts from Corepack, that would definitely be a bug, please report it.

[Qwarctick]

OK thanks.

The problem seems to be that corepack does not default to the version of yarn installed by the corepack yarn@4.x install command. It tries to install yarn 1.1 and fails. It seems to need the packageManager field in the package.json. But this field doesn't seem to support syntheses like 4.X.

[Qwarctick]

Ok we fallback in the problem with the semver in packageManager :

• https://github.com/nodejs/corepack/issues/95