Gitlab docker-runner does not mount uppercase symlinks to devices correctly

Summary

Gitlab docker runner does not mount uppercase symlinks to devices correctly

Steps to reproduce

  1. Prequisites:
  • Gitlab-runner on Linux (here: Ubuntu Disco)
  • Docker
  • Gitlab-runner with Docker socket mounted into it, so it can build silbling containers
  1. Udev rule: Create udev rule for existing device (example: /dev/ttyUSB0 of a serial interface). That creates a SYMLINK to 'ttyUSB_Customname`
  2. Mount the device (/dev/ttyUSB0) as well as the symlink (/dev/ttyUSB_customname) with settings in the Gitlabs config.toml
  3. Build a project that uses an image and build stepts that somehow use the device (example: file /dev/ttyUSB0, file /dev/ttyUSB_Customname)

The result: /dev/ttyUSB0 will show up and is working, /dev/ttyUSB_Customname is not existant in the container at all.

(How one can reproduce the issue - this is very important)

Example Project

What is the current bug behavior?

... but wait, there is more: If we turn up the gitlab-ci build level to debug we see a log output that tells us that /dev/ttyusb_customname is being mounted onto /dev/ttyusb_customname - wait a minute, why the lowercase? If I create a lowercase symlink rule, instead of the case sensitive one - it actually works!

What is the expected correct behavior?

Being able to mount symlinks to devices that include uppercase (What you should see instead)

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info 
(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:env:info)


(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production)

Results of GitLab application Check

Expand for output related to the GitLab application check 
(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)


(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)


(we will only investigate if the tests are passing)

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)