By running containers in a rootless docker context as root. This is
because user and group IDs are remapped in the user namespaces uses by
rootless docker, and it's unlikely that the current user ID will map to
the same ID under this remap (see docs[1] for some more details).
Specifically, it means ownership of mounted volumes will not be for the
current user and trying to write can result in permission errors.

This change borrows heavily from an existing PR[2].

The output format of `docker system info` I don't think is
documented/guaranteed anywhere, but it should corresponding to the
format of a `/info` API request to Docker[3]

The added test _hopes_ to avoid regressions in this behaviour, but since
tests aren't run in a rootless docker context on the PR checks (and I
couldn't find an easy way to make it the case) there's still a risk of
regressions sneaking in.

Link: https://docs.docker.com/engine/security/rootless/ [1]
Link: pre-commit#1484 [2]
Link: https://docs.docker.com/reference/api/engine/version/v1.48/#tag/System/operation/SystemAuth [3]
Co-authored-by: Kurt von Laven <Kurt-von-Laven@users.noreply.github.com>
Co-authored-by: Fabrice Flore-Thébault <ffloreth@redhat.com>

tmeijn pushed a commit to tmeijn/dotfiles that referenced this pull request