Agenda for the Flatcar Developer Sync on Wednesday, 25th of June 2025, 2:30pm UTC

[t-lo]

In our monthly Flatcar developer syncs maintainers review development / roadmap progress, discuss special projects like OS composability, secure / trusted boot, vendor support, and CNCF incubation status. We provide an overview of ongoing work, give an outlook of future work, and plan the next release.

Join if you're curious about current or future Flatcar development and/or to raise visibility of a feature, bug, or PR.

• Jitsi Link: https://meet.flatcar.org/OfficeHours
• Youtube live stream / recording: https://www.youtube.com/live/f2h-VxoS76I
  • All recordings: https://www.youtube.com/@FlatcarLinux/live
• Community Calls calendar (all future calls): link
  • iCal version: link

Welcome

• Brief intro/check-in of the new participants in the Jitsi call. Please introduce yourself and share what brings you here today.

News and Announcements

End of support for CGroupsV1 in Stable released TODAY

Flatcar will stop supporting the cgroups v1 backwards compatibility mode in 2025.

• With our adoption of systemd-256, support for legacy CGroupsV1 will end in Alpha, Beta, and eventually Stable.
• Current Alpha and Beta releases do not support CGroupsV1 anymore. The next major stable release also won't.
• LTS-2024 (4081.3.x) will support CGroupsV1 until late 2025.
• Enabling legacy CGroupsV1 during deployment will not be supported anymore.
• Nodes that use CGroupsV1 legacy mode will fail to update. This ensures your workloads will not be disrupted. Enable CGroupsV2 on your legacy CGroupsV1 nodes in order to successfully update.

Monthly Contributions and Advisory status Review

1. Discuss the latest Monthly Contributions Report
   • Also see https://insights.lfx.linuxfoundation.org/foundation/cncf/overview/github?project=flatcar&repository=&routedFrom=Github
   • 3 First-Time Contributors in the last month:
     • @anttiharju - website typo fix
     • @subnix - Podman support for toolbox
     • @robinschneider - docs / spelling corrections for sysext bakery skeleton script
2. Review of last month's advisory stats in the latest Contributions Report
   a. Advisory status and planning: Flatcar tactical, release planning, and roadmap (view)

Ongoing and Planned Tasks Review

Discussion

1. Roadmap review: Flatcar tactical, release planning, and roadmap (view) (@t-lo, @miao0miao )
2. Projects status review:
   a. Composable OS: sysext and ClusterAPI (@t-lo) - Flatcar tactical, release planning, and roadmap (view)
   b. SecureBoot / Trusted Boot (@sayanchowdhury ) - Flatcar tactical, release planning, and roadmap (view)
   c. CNCF Incubation process (@miao0miao) - Flatcar tactical, release planning, and roadmap (view)
   d. Flatcar infrastructure status (@tormath1) - Flatcar tactical, release planning, and roadmap (view)
   e. Nebraska status (@ErvinRacz) - Flatcar tactical, release planning, and roadmap (view)
3. Maintainer team tactical / implementation (aka "line work") status review (@sayanchowdhury): Flatcar tactical, release planning, and roadmap (view)

Open Mic: Work to assign / User issues and PRs to discuss?

• Boot partition increase Increase partition sizes scripts#3027 and kernel move to /usr https://hackmd.io/@flatcar/H1MDJuu7lg (@ader1990 and @chewi)
• "Flatcar Community Maintenance Mode" this Friday The Maintenance Mode on Friday, June 27th 2025 [All Day] #1784

Release Planning

• Ongoing and upcoming releases tracker: (Flatcar tactical, release planning, and roadmap (view)) (@sayanchowdhury)
• Talk about the upcoming release and the status of the packages
• Status of the ongoing release
• Preparation of the next release

Q&A

• Questions from community participants, answered by the Flatcar maintainers

Administrative tasks after meeting concluded

• Create a new Github discussion for the next Flatcar developer sync: https://github.com/flatcar/Flatcar/discussions/new?category=flatcar-developer-sync
• Close this discussion as "Resolved".

[t-lo]

Discussion / feedback on kernel move to solve boot partition size issue:

• ship kernel via /usr, launch via singed script.
• What about rollback?
  • update ships a load_old script to fall back old booting scheme
• Phased introduction
  • old bootloader boots with new scheme
  • new bootloader keeps supporting previous scheme during the transition period
• Would enable safe(ish) bootloader upgrades
  • UEFI Shim might save us because it would boot a fallback grub we provide
  • BIOS: safe grub updates aren't feasible because there is no shim, but we can work around this by providing a custom Grub script via the OEM partition. Alternatively, require users to update manually.
• Fedora CoreOS forces a manual bootloader upgrade, i.e. users need to run a command to do it
  • We might use a similar scheme and make grub updates opt-in, or even manual
• In any case needs thorough testing on a wide diversity of hardware

TODO:

• add a migration plan to the proposal: https://hackmd.io/@flatcar/H1MDJuu7lg
• ensure thorough testing, particularly on bare metal
• In the meantime, get boot partition resize PR merged and ensure that we continue testing with the old, smaller sizes.