Incorrectly detecting wsl when systemd is enable

[raypappa]

pre-commit-terraform/hooks/_common.sh

Line 210 in e41252b

! -f /proc/sys/fs/binfmt_misc/WSLInterop ]]; then # WSL have cfs_quota_us, but WSL should be checked as usual Linux host

Hello! I'm encountering an issue in detecting wsl and setting the cores. When systemd is enable the file is WSLInterop-late.

[MaxymVlasov]

Hi
Thanks for reporting

Can you please double check that there is no other files started from
/proc/sys/fs/binfmt_misc/WSLInterop?

If so, we can adjust check to ! -f /proc/sys/fs/binfmt_misc/WSLInterop* or something similar.

Or maybe WSL have some other WSL-specific file/output that always exist and signals that it's a WSL.

If uname -a produces output with WSL in it - please share it with us too

[yermulnik]

@raypappa Can you please show the output of ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop* command?

[yermulnik]

Linking just for reference: mozilla-ai/llamafile#275 — so we need to check either one or another not exist, right? 🤔

[raypappa]

it's possible to compile a custom kernel for wsl, I've not done it so I don't know what the uname is like for that.

$ uname -r
5.15.167.4-microsoft-standard-WSL2

 ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*
-rw-r--r-- 1 root root 0 Apr  3 09:54 /proc/sys/fs/binfmt_misc/WSLInterop

I then created /etc/wsl.conf and enabled systemd for it and this is now the output

ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*
-rw-r--r-- 1 root root 0 Apr  5 17:47 /proc/sys/fs/binfmt_misc/WSLInterop-late

In wsl you can configure startup settings for the distro using /etc/wsl.conf. However by default it's not present.

By default wsl will automount the windows host drives under /mnt such as /mnt/c

relavant issues too microsoft/WSL#4071

my mounts also have this too

cat /proc/mounts | grep /usr/lib/modules
none /usr/lib/modules/5.15.167.4-microsoft-standard-WSL2 overlay rw,nosuid,nodev,noatime,lowerdir=/modules,upperdir=/lib/modules/5.15.167.4-microsoft-standard-WSL2/rw/upper,workdir=/lib/modules/5.15.167.4-microsoft-standard-WSL2/rw/work 0 0

I can also disable interop in wsl.conf at which point i get this

ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*
ls: cannot access '/proc/sys/fs/binfmt_misc/WSLInterop*': No such file or directory

EDIT: most people want to have interop enabled and it's enabled by default.

[yermulnik]

@raypappa Can you check if the 759fcb7 fixes the issue in your conditions (#872)? Thanks.

Can you additionally please post the output of cat /proc/version with both systemd enabled and disabled so that we can consider which option to detect WSL is better? Thanks.

UPD: edited again this comment to provide id of the latest commit from the branch.

[raypappa]

I tested all 4 permutations of boot.systemd true/false and interop.enabled true/false

All 4 worked.

What I did find interesting was that in some circumstance I still had an interop file when interop was disabled.

# 'cat /etc/wsl.conf'
[boot]
systemd=true
[interop]
enabled=false
appendWindowsPath=false

########################################
# 'cat /proc/version'
Linux version 5.15.167.4-microsoft-standard-WSL2 (root@f9c826d3017f) (gcc (GCC) 11.2.0, GNU ld (GNU Binutils) 2.37) #1 SMP Tue Nov 5 00:21:55 UTC 2024
########################################
# 'ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*'
ls: cannot access '/proc/sys/fs/binfmt_misc/WSLInterop*': No such file or directory
########################################
# 'pre-commit run -a'
Terraform fmt............................................................Passed
########################################

# 'cat /etc/wsl.conf'
[boot]
systemd=false
[interop]
enabled=false
appendWindowsPath=false

########################################
# 'cat /proc/version'
Linux version 5.15.167.4-microsoft-standard-WSL2 (root@f9c826d3017f) (gcc (GCC) 11.2.0, GNU ld (GNU Binutils) 2.37) #1 SMP Tue Nov 5 00:21:55 UTC 2024
########################################
# 'ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*'
-rw-r--r-- 1 root root 0 Apr  6 13:14 /proc/sys/fs/binfmt_misc/WSLInterop
########################################
# 'pre-commit run -a'
Terraform fmt............................................................Passed
########################################

# 'cat /etc/wsl.conf'
[boot]
systemd=true
[interop]
enabled=true
appendWindowsPath=false

########################################
# 'cat /proc/version'
Linux version 5.15.167.4-microsoft-standard-WSL2 (root@f9c826d3017f) (gcc (GCC) 11.2.0, GNU ld (GNU Binutils) 2.37) #1 SMP Tue Nov 5 00:21:55 UTC 2024
########################################
# 'ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*'
-rw-r--r-- 1 root root 0 Apr  6 13:16 /proc/sys/fs/binfmt_misc/WSLInterop-late
########################################
# 'pre-commit run -a'
Terraform fmt............................................................Passed

# 'cat /etc/wsl.conf'
[boot]
systemd=false
[interop]
enabled=true
appendWindowsPath=false

########################################
# 'cat /proc/version'
Linux version 5.15.167.4-microsoft-standard-WSL2 (root@f9c826d3017f) (gcc (GCC) 11.2.0, GNU ld (GNU Binutils) 2.37) #1 SMP Tue Nov 5 00:21:55 UTC 2024
########################################
# 'ls -l1 /proc/sys/fs/binfmt_misc/WSLInterop*'
-rw-r--r-- 1 root root 0 Apr  6 13:21 /proc/sys/fs/binfmt_misc/WSLInterop
########################################
# 'pre-commit run -a'
Terraform fmt............................................................Passed
########################################

The PR fixes my issue and I like the addition or checking /run/WSL. My concern about checking /proc/version is if someone is running a custom wsl kernel instead of the Microsoft provided one.

[raypappa]

Compiled a new kernel. this is the /proc/version

Linux version 6.6.84.1-microsoft-standard-WSL2+ (stoney@platypus) (gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40) #3 SMP PREEMPT_DYNAMIC Sun Apr  6 13:55:34 PDT 2025

[yermulnik]

My concern about checking /proc/version is if someone is running a custom wsl kernel instead of the Microsoft provided one.

Then let's stick with checking those three files at the moment and adjust if necessary if we receive reports.
Please add your formal approval to #872 as the request owner 🤝

[antonbabenko]

This issue has been resolved in version 1.98.1 🎉