Flatcar Container Linux

May 26, 2026 · View on GitHub

Note: To file an issue for any Flatcar repository, please use the central Flatcar issue tracker.

Flatcar Container Linux

Welcome to the Flatcar community! Whether you're a user, contributor, or just curious — we're glad you're here! 👋

Flatcar Container Linux is a fully open source, minimal-footprint, secure by default and always up-to-date Linux distribution for running containers at scale.

Flatcar ships only the essentials needed to run containers — no package manager, no configuration drift. Its immutable, read-only filesystem minimizes attack surfaces, and atomic, automated updates keep your system secure and up-to-date without manual intervention.

New to Flatcar?

If you've never heard of image-based or immutable Linux, here's a quick orientation:

What makes Flatcar different? Unlike general-purpose distros, Flatcar has no package manager (apt, yum, etc.) and its root filesystem is read-only. You declare the state you want at boot time (via Ignition) and the OS atomically applies it. Updates happen automatically in the background and take effect on the next reboot — no manual patching required.
Who uses Flatcar? Primarily teams running container workloads (Kubernetes, Docker, etc.) in cloud or on-prem environments where security, reproducibility, and low maintenance overhead matter.

Want a guided tour? These talks are great starting points:

Video	Speaker	Description
So Flatcar's in the CNCF... What's Next?	Andrew Randall (Cloud Native Rejekts 2024)	Project status, CNCF acceptance, governance, roadmap, and future direction
Flatcar Linux 101: A Hands-Free Server OS	Brian Exelbierd (InstallfestCz 2026)	Core concepts, Ignition provisioning, automatic updates, and sysext extensions
Take the Power Back on Your Containers with Flatcar	Mathieu Tortuyaux, Microsoft (Linux Foundation)	Hands-on tutorial: deploy with Terraform, provision with Ignition, set up auto-updates via Nebraska

Don't forget to check out flatcar.org for documentation, guides, and other useful resources!

Flatcar Container Linux

Install and Operate Flatcar

Flatcar Container Linux has a dedicated documentation site. Start here:

Getting Started — covers Ignition, local testing with QEMU, automatic updates, and cloud providers

Resource	Link
Current Releases	flatcar.org/releases
Interoperability Matrix	interop-matrix.md
CIS Benchmarks	CIS reports

Communication Channels

We're a friendly bunch and always excited to chat! Here's where you can find us:

Channel	Link
Discord (preferred)	discord.gg/PMYjFUsJyq — text, voice & video with contributors and maintainers
Slack	#flatcar (Kubernetes Slack) / #flatcar (CNCF Slack)
GitHub Discussions	flatcar/Flatcar/discussions
Mailing List (Users)	flatcar-linux-user

💡 Want to report a bug or request a feature? File an issue. Have a question or not sure where to start? Jump into one of our chats and ask — we're happy to help!

Platform	Link
Mastodon	@flatcar@hachyderm.io
Bluesky	@flatcar.org
X	@flatcar

Community Meetings

Come say hi! Check our Google Calendar (iCal) for all meeting times.

Office Hours


When	2nd Wednesday of every month at 2:30pm UTC (double check calendar)
Where	meet.flatcar.org/OfficeHours (all you need is a browser, no installations/accounts required)
Agenda	Office Hours Discussions

Engage with the Flatcar community, learn about project directions, discuss contributions, and catch occasional demos of image-based Linux technologies. Each call includes a brief Release Planning update.

Developer Syncs


When	4th Wednesday of every month at 2:30pm UTC (check calendar)
Where	meet.flatcar.org/OfficeHours (all you need is a browser, no installations/accounts required)
Agenda	Developer Sync Discussions

Backlog grooming, task planning, roadmap discussions, and day-to-day issues. If you want to get hands-on with development, this is the call for you!

🎥 All meetings are live-streamed on YouTube — recordings are linked in each meeting's agenda.

Report Bugs and Request Features

Found a bug or have a feature request? File an issue — please select the appropriate issue type to help us triage.

💡 Tip: Want a new package in the base image? Use the "New Package Request" issue type and check out the package addition guidelines.

Participate and Contribute

Thinking of making a contribution? Engage with the project early — comment on an existing issue or create a new one. Making your intent visible is often the key to getting your work accepted!

For full details, check out our Contributing Guide which covers:

Topic	What you'll find
Ways to Contribute	Code, docs, community, outreach, and more
Finding Issues	Labels like `good first issue` and `help wanted`
Development Setup	SDK walkthrough and developer guides
PR Lifecycle	From filing to merge
Commit Guidelines	Format, style, and best practices

🌟 New to Flatcar? Consider building a Flatcar App — a great hands-on way to learn!

Becoming a Maintainer

The Flatcar maintainer path is laid out in our governance document.

Repository Overview

The Flatcar project is spread across many repositories in the flatcar GitHub organisation. For a full map of repos grouped by function, see the Repository Overview in the Contributing Guide.

Project Status and Roadmap

Board	Description
Issue Tracker	Short-term concerns — bugs and minor enhancements
Tactical Board	What maintainers and contributors are currently working on
Release Board	Completed items assigned to upcoming releases
Releases Tracker	Track the status of each release across all channels
Roadmap Board	Epics, major features, and long-term items

Release Process

Flatcar Container Linux follows an Alpha → Beta → Stable release process:

New features and major version upgrades enter Alpha, transition to Beta, then land in Stable.
Bug fixes are released directly to the affected channel (Alpha fixes go to Alpha, Beta to Beta, Stable to Stable).

Within each channel, updates are planned on a 14-day cadence. Major releases follow a broader rhythm:

Promotion	Target cadence
New major Alpha	Monthly
Alpha → Beta	Every 2 months
Beta → Stable	Every 3–4 months
New LTS	Yearly

Up-to-date planning status is reflected in our release planning board. For the full release process documentation, see the Release Guide.

LTS

Some users prefer to avoid frequent version upgrades. The Flatcar LTS channel provides a longer support window:

Detail	Value
Based on	A "golden Stable" release
Maintenance period	18 months
New LTS frequency	Every 12 months
Upgrade window	6 months overlap

Project Governance

Flatcar is a community-driven project. Every participant — bug reporter, feature requester, code contributor — is considered a contributor. Maintainers have commit access and help govern the project, driving it forward and maintaining its scope and vision.

For full details see our governance document.

Resource	Link
Governance	governance.md
Maintainers	MAINTAINERS.md
Security Policy	SECURITY.md

Code of Conduct

We follow the CNCF Code of Conduct.

Please contact the private Maintainer mailing list or the Linux Foundation mediator, Mishi Choudhary (mishi@linux.com), to report an issue.

Reference

Document	Description
CONTRIBUTING.md	How to contribute — finding issues, development setup, PR lifecycle, commit guidelines
RELEASES.md	Release channels, downloads, and the release process
governance.md	Project governance model, maintainer roles, and decision-making
MAINTAINERS.md	Current list of project maintainers
EMERITUS_MAINTAINERS.md	Former maintainers who have stepped down
ONBOARDING.md	Checklist for onboarding new maintainers
SECURITY.md	Security policy and vulnerability reporting
CODE_OF_CONDUCT.md	CNCF Code of Conduct
adding-new-packages.md	Guidelines for requesting and adding new packages to Flatcar
interop-matrix.md	Platform and provider interoperability matrix
CODEOWNERS	Code ownership and review assignments
LICENSE	Project license (Apache 2.0)