Mount / as Shared by default?

[mangkoran]

Windows Build Number

Microsoft Windows [Version 10.0.22000.194]

WSL Version

• WSL 2
• WSL 1

Kernel Version

5.10.55-xanmod1-microsoft-standard-WSL2

Distro Version

ArchWSL

Other Software

• podman 3.3.1-1

Repro Steps

1. Install podman
2. Configure podman to use rootful mode (Reference)
3. Run any container, for convenience I exec podman run docker.io/hello-world

Expected Behavior

Container run successfully without warning.

Actual Behavior

Container run successfully with warning:

> podman run hello-world
WARN[0000] "/" is not a shared mount, this could cause issues or missing mounts with rootless containers

Diagnostic Logs

No response

[Biswa96]

I think you are looking for cross distro mount which can be enabled in /etc/wsl.conf file by adding this

[automount]
crossDistro = true

More here https://docs.microsoft.com/en-us/windows/wsl/release-notes#build-18970

[mangkoran]

Thank you, but I didn't found /etc/wsl.conf in my distro. Is it supposed to be there? Also I think this release note is also related to my issue.

Add support for mount propagation flags [GH 2911].

[Biswa96]

That /etc/wsl.conf file has to be created manually.

[mangkoran]

I have created and added lines to /etc/wsl.conf and done wsl --shutdown, but it still showing / propagation is private:

~
> cat /etc/wsl.conf
[automount]
crossDistro = true


~
> findmnt / -o PROPAGATION,TARGET
PROPAGATION TARGET
private     /

[mangkoran]

I found this on the web. Seems like the default mount propagation is indeed "private", but in systemd-ful OS systemd will change the mount propagation to "shared" (Reference). I think we could use bash script to do this instead, but I'm not too proficient in shell scripting.

[KnairWang]

I find a way to solve this issue, by adding a boot command "mount --make-rshared /" into wsl.conf
(reference Build 21286)

~
❯ podman ps
CONTAINER ID  IMAGE       COMMAND     CREATED     STATUS      PORTS       NAMES

~
❯ cat /etc/wsl.conf
[boot]
command="mount --make-rshared /"

I suppose after updating the /etc/wsl.conf, you may need run wsl --shutdown on Windows side to make the change work in WSL.

[mangkoran]

@KnairWang I have tried your solution (or workaround?) and it works!. Thank you very much.

However, this solution (or workaround?) is might be the best we could have for systemd-less WSL distro. As WSL recently added native systemd support, I found that this issue still persist.

Closing this ticket and moving the issue for systemd-ful WSL distro to #8922.