In Fedora 40, Podman has undergone a major version upgrade to v5 [1],
introducing some breaking changes. Notably, CNI networking support has been
discontinued in favor of Netavark, and cgroups v1 support has been
deprecated in favor of cgroups v2.
To know whether your nodes are affected, you can use podman info and look
for the cgroupVersion and networkBackend keys.
If you're using cgroups v1, migrating to cgroups v2 is strongly
recommended, as a future Podman version will no longer support cgroups v1.
Kernel arguments can be adjusted to use cgroups v2 with rpm-ostree kargs
[2].
If you're using CNI networking, transitioning to Netavark requires
running podman
system reset --force, leading to the deletion of images, containers, and
custom networks. Depending on your setup, it may be preferable to
reprovision the entire machine from the latest images to allow for Ignition
to bring up containerized applications from scratch.
If you have any feedback or encounter issues related to the aforementioned
changes, please don't hesitate to participate in the upstream issue
discussion [3].
The Fedora CoreOS Team
[1] https://fedoraproject.org/wiki/Changes/Podman5
[2]
https://docs.fedoraproject.org/en-US/fedora-coreos/kernel-args/#_removing_e…
[3] https://github.com/coreos/fedora-coreos-tracker/issues/1629
