Yarn fails and doesn't provide information when running inside Docker

[felixsanz]

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

An unexpected error occured, please open a bug report with the information provided in "/usr/src/app/yarn-error.log".

If the current behavior is a bug, please provide the steps to reproduce.

I don't know, I can't check the error :)

What is the expected behavior?

It should print errors directly to stdout/stderr. I'm trying to build a Docker image and it fails. But since this happens inside the container (and destroyed on the error step), I can't check that yarn-error.log because it doesn't exist anymore.

Please mention your node.js, yarn and operating system version.

Yarn 0.16.1 using Docker

[Daniel15]

Hi @felixsanz! Is that happening when you run yarn install in the Docker container? You could try cat the log file when the error occurs, and see what it contains. I recently wrote some end-to-end tests for Yarn using Docker (#1391) and this is what I did via a fail_with_log utility function:

#!/bin/bash
# Executed within a fresh Docker container to test execution of Yarn.
# Should be executed after Yarn has been installed.
set -ex

fail_with_log() {
  # Include the yarn-error.log file in the output, if available
  exitcode=$?
  if [ -s yarn-error.log ]; then
    cat yarn-error.log
  fi;
  exit $exitcode
}

cd /tmp
mkdir yarntest
cd yarntest
yarn add react || fail_with_log

Is your container running Ubuntu by any chance? If so, you'll need to install the ca-certificates package in order for TLS/SSL to work from Node.js. That's the issue I encountered when trying to run Yarn in Docker 😄

[Daniel15]

The other alternative is to mount a directory (-v flag to docker run) and run Yarn in that directory. Then you'll be able to look at the log file on your host machine.

[felixsanz]

I'm gonna close this because deleting the yarn.lock file fixed the issue and i don't get the error anymore. Probably it was messed up while i was trying builds. If happens again i'll try your suggestions and comment here again. Thanks!

[JoshuaKGoldberg]

I'm in a similar situation with VSTS build machines. @Daniel15 your suggested steps are great 😊 thanks!

I resolved the problem by adding a cmd task that runs if a previous task has failed and prints the contents of yarn-error.log if it exists:

if exist yarn-error.log echo "Found error output in yarn-error.log:" && type yarn-error.log && del yarn-error.log

Edit: ...and a PowerShell equivalent:

$yarnErrorFile = "yarn-error.log"

if (Test-Path $yarnErrorFile)
{
    Write-Output "Found error output in $yarnErrorFile"
    Get-Content $yarnErrorFile | Write-Output
    Remove-Item $yarnErrorFile
}

[nkalinov]

Fast forwarding to 2022 and Yarn 2+ that's what helped me debug the issue: yarn install --inline-builds https://yarnpkg.com/cli/install#options-inline-builds