Ensure the consistent setting of the HOME env variable on container start

[daw1012345]

Does this PR introduce a user-facing change?

Fixes an issue where the HOME environment variable would be configured inconsistently between container starts if a new passwd entry had to be created for the container

Description

Podman sets the HOME environment variable to the home directory of the user executing the podman command (if it is mounted) only if a new passwd entry has to be added on start. After a container restart, HOME is set to the home directory of the user configured with the --user flag.

Reproduction/Example

Impact

This impacts tools such as VSCode Dev Containers as they use this variable to decide where to place files (the vscode server in this case). This issue is particularly annoying for people using Dev Containers and toolbox as a restart causes VSCode to place the server in a different place, often /root where it does not have write permissions.

Solution

Set the HOME env variable on container creation, prioritized in the following order:

1. Existing HOME env variable
2. Home folder of the user executing the podman command
3. Home folder of the user specified with the --user flag

[rhatdan]

@n1hility @vrothberg @containers/podman-maintainers PTAL

[giuseppe]

I don't think we want to honor the home folder of the user executing the command. The order should be:

1. Existing HOME env variable
2. Home folder of the user specified with the --user flag

The issue with using the current user home directory is that the same command would have different behaviors on different machines. If you want to override the home directory, just specify it on the command line

[Luap99]

I agree with @giuseppe, it doesn't seem to make sense to set the home based on the user executing the command.

This seems to be a simple bug when the container is created with --userns keep-id -v $HOME:$HOME --user 0:0 so I think we should just fix that.

[daw1012345]

The issue with using the current user home directory is that the same command would have different behaviors on different machines. If you want to override the home directory, just specify it on the command line

This indeed makes more sense. I've adjusted the PR to reflect this - the home directory of the caller is no longer considered.

[baude]

does it make sense to move this and the stanza below "up"?

[baude]

if this is only used once, can it just be inline?

[Luap99]

I think a separate function is better.

[baude]

/approve

LGTM, small nits identified

[Luap99]

I think a separate function is better.

[Luap99]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: baude, daw1012345, Luap99

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[debarshiray]

Kudos for adding the tests, @daw1012345 !

[debarshiray]

I arrived here from containers/toolbox#1296 Since this pull request explicitly mentions Toolbx, I thought that I would leave my doubt here as well for the sake of my future self and anybody else who might be following along.

Set the HOME env variable on container creation, prioritized in the
following order:

Existing HOME env variable
Home folder of the user executing the podman command
Home folder of the user specified with the --user flag

I don't think we want to honor the home folder of the user executing
the command. The order should be:

Existing HOME env variable
Home folder of the user specified with the --user flag

I don't understand what home folder of the user executing the podman command means. Are we talking about the user on the host who invoked podman create, podman start, etc.?

If so, wouldn't the HOME environment variable on the host be this user's home directory in the vast majority of cases? I don't understand how HOME is different from the home folder of the user executing the podman command.

Are you thinking of cases where someone might have (temporarily?) overridden HOME on the host to point to something other than their home directory for testing and such?

The issue with using the current user home directory is that the same
command would have different behaviors on different machines.

I don't understand this. HOME can also be different on different machines. How is HOME different from the current user home directory?