Improving Podman users experience: avoid setting $HOME

[l0rd]

Hi 👋, I am Mario, and I am a Podman maintainer.

Kudos to the team for the Dev Containers extension 🚀. It's a great project, and we look forward to collaborating to improve Podman users' UX.

For this reason, I am trying to find a solution to avoid having to explicitly set $HOME in a .vscode/devcontainer.json to successfully start a Dev Container with Podman (this workaround is mentioned in the documentation).

Currently, if a user doesn't set $HOME in the devcontainer.json, the container startup fails because the extension tries to create a folder in /root instead of $HOME:

mkdir: cannot create directory '/root': Permission denied

Steps to Reproduce:

1. Configure Dev Containers extension to use podman as described in doc
2. Locally clone the repository https://github.com/microsoft/vscode-remote-try-go and open it in VS Code
3. Open the command palette and select Dev Containers: Open Folder in Container

Analyzing the failure

This is what I could infer from the Dev Containers log and may not be 100% accurate but those are the steps that preceded the error:

1. The container is started and, as a user is not specified, the default (root) is used
2. The extension inspects the container and reads the Config.Env["HOME"] to infer $HOME:
   • when it's Podman HOME=/root
   • when it's Docker HOME is not set
3. The extension runs a podman/docker exec command, as user vscode, to create the folder $HOME/.vscode-server/bin`
   • when it's Podman the flag --env=HOME=/root is passed to the exec command
   • when it's Docker the flag --env=HOME=/home/vscode is passed to the exec command

Podman sets HOME=/root when starting the container. But this is intended: when $HOME is unset, Podman sets it based on/etc/passwd. This is a valuable feature as many command line tools expect $HOME to be set.

Proposals to address the problem

Avoid inspecting the $HOME environment variable, of a container started as an arbitrary user (often this means root), to infer the $HOME variable to use with user vscode.

---

• VSCode Version: 1.96.4
• Local OS Version: macOS 15.3
• Remote OS Version: Fedora 41
• Remote Extension/Connection Type: Dev Containers

[chrmarti]

Hi Mario, thanks for investigating! To avoid breaking existing devcontainers we could check if the user has write access on $HOME and ignore the variable if not.

[l0rd]

@chrmarti thank you for looking at this 🙌. Sure, this should be fine too!

Another option would be to figure out if you are talking with Podman (using the ping API for example) and avoid inferring $HOME by inspecting when it's the case. It may be overkill for this particular issue, but it would help in the future if you want to provide better Podman support.