imagestore not picked up correctly when graphroot contains an environment variable?

[livingsilver94]

This is my storage.conf:

[storage]
driver = "overlay"
graphroot = "$XDG_RUNTIME_DIR/containers"
###imagestore = "$XDG_RUNTIME_DIR/containers"
runroot = "$XDG_RUNTIME_DIR/containers/storage"
transient_store = true

[storage.options]
additionalimagestores = ["/media/containers"]

[storage.options.pull_options]
use_hard_links = "true"

And the error I get is

Error: configure storage: open /media/containers/overlay-images/images.lock: open /media/containers/overlay-images/images.lock: permission denied

It seems podman tries to write into the read-only additional image store because it didn't pick up the correct path of imagestore, that should be equal to the graphroot when unspecified (in fact, it' commented out).

When I uncomment imagestore, it tries to write the $XDG_RUNTIME_DIR and fails, which is fine because the documentation doesn't actually state environment variables are supported for this configuration entry.

Expected behavior

Podman should use $XDG_RUNTIME_DIR/containers (with the envvar resolved) for the image store.

[github-actions]

This repository has been migrated to https://github.com/containers/container-libs. Please open your issue there.