Switching release channels

Flatcar Container Linux is designed to be updated automatically with different schedules per channel. You can disable this feature, although we don't recommend it. Read the release notes for specific features and bug fixes.

By design, the Flatcar Container Linux update engine does not execute downgrades. If you're switching from a channel with a higher Flatcar Container Linux version than the new channel, your machine won't be updated again until the new channel contains a higher version number.

Update Timeline

Create update config file

You can switch machines between channels by creating /etc/coreos/update.conf:


Restart update engine

The last step is to restart the update engine in order for it to pick up the changed channel:

sudo systemctl restart update-engine


After the update engine is restarted, the machine should check for an update within an hour. You can view the update engine log if you'd like to see the requests that are being made to the update service:

journalctl -f -u update-engine

For reference, you can find the current version:

cat /etc/os-release