Subject: Podman v5 breaking changes

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].

[1] https://fedoraproject.org/wiki/Changes/Podman5
[2] https://docs.fedoraproject.org/en-US/fedora-coreos/kernel-args/#_removing_existing_kernel_arguments
[3] https://github.com/coreos/fedora-coreos-tracker/issues/1629

DWM: Maybe link to the tracker issue (this will let people know where to chime in with feedback/issues).
GM: Mentioned the upstream issue in the last paragraph.
DWM: Should we mention the CLHM helpers that we are going to be shipping soon that will alert users when they need to take action?