WSL prerelease breaks docker startup init with ulimit -Hn 524288

[borjamunozf]

Windows Version

10.0.22631.5335

WSL Version

2.5.7

Are you using WSL 1 or WSL 2?

• [x] WSL 2
• [ ] WSL 1

Kernel Version

No response

Distro Version

Ubuntu 24.04

Other Software

No response

Repro Steps

1. Same file /etc/wsl.conf including

[boot]
command = "service docker start; service cron start; vcan"
...

2. Update to prerelease from 2.4.10
3. Shutdown wsl
4. Start distro again shows Docker service down, failed to start because **/etc/init.d/docker:62 ulimit: error setting limit (Invalid argument)
5. Faulty command: ulimit -Hn 524288
6. Run that command manually also shows: -bash: ulimit: open files: cannot modify limit: invalid argument

Expected Behavior

Docker service is able to start at boot like in previous releases (2.4.10 latest one I tested)

Actual Behavior

Docker service cannot start at boot after updating to prelease 2.5.7, but it can be started manually afterwards:

sudo service docker restart

Diagnostic Logs

Docker info

Client: Docker Engine - Community
 Version:    28.1.1
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.23.0
    Path:     /usr/libexec/docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.35.1
    Path:     /usr/libexec/docker/cli-plugins/docker-compose

OS Release:

PRETTY_NAME="Ubuntu 24.04.2 LTS"
NAME="Ubuntu"
VERSION_ID="24.04"
VERSION="24.04.2 LTS (Noble Numbat)"
VERSION_CODENAME=noble
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=noble
LOGO=ubuntu-logo

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[borjamunozf]

Possible linked? https://github.com/microsoft/WSL/issues/12837

[benhillis]

@OneBlue - I think you tweaked some ulimit values recently?

[OneBlue]

Yes this is indeed a consequence of that. We have increased the soft file descriptor limit to 1,048,576, and given that the hard file descriptor limit cannot be lower than the soft one (which is what ulimit -Hn 524288 is trying to do), that command fails.

Maybe 1,048,576 is a bit too high. I'll make a change to bring it down to let's say 10240. That should solve this while not regressing #12837

[daulis]

This is also affecting multiple people at my company. Because 2.5.7 is flagged as a regular, non-prerelease it means more people will be using this version soon too.

I can reproduce this on 1 of my 2x work PCs. For the PC that I can reproduce this on, I confirmed that rolling back to 2.5.6 works Both of my PCs (including the one that shows this problem, and the one that doesn't show this problem) are on Windows 11 23H2

[daulis]

@OneBlue I tested and confirmed that 2.5.8 fixes this issue, for my scenario. Thank you for the quick response!

Currently, 2.5.7 is flagged as Latest, and 2.5.8 is Pre-release. Could 2.5.8 be marked as Latest? It would be nice for users to update to the fixed version when running wsl --update.

[OneBlue]

Glad to hear @daulis. We need to do some additional testing before that release can be marked as Latest, but you can upgrade with wsl --update --pre-release in the meantime.

[OneBlue]

Closing since the issue is resolved in 2.5.8