CT - custom update group name

[MattCrum1]

Description

I'm setting up Nebraska to control updates on Flatcar instances and want to make use of Update Groups to control when updates are available to specific customers.

I have done a script to convert some host details into an Ignition YML file, which I feed into CT using Docker. It looks like CT does not support custom update group names?

• Setting the group name to "testgroup" or the ID of one of the Nebraska groups results in an error: "unknown update group".
• Setting the group name to "stable" works fine.

Impact

Cannot set custom Update Groups for new machines via Ignition Script. Also read something on here about custom group names being overwritten with "stable" after upgrade; want to make sure that the custom group name is in the container-linux configuration properly.

Environment and steps to reproduce

Create YML file including a non-standard update group name:

update:
group: testgroup

Feed file into ct and see error.

Change the YML file to have a standard group name:

update:
group: stable

Feed file into ct and the error does not occur.

[MattCrum1]

Worth noting that manually updating the JSON afterwards with the custom group name works fine; the new Flatcar machine has the name in /etc/flatcar/update.conf

[pothos]

That should work and maybe we need to fix something in ct.
As workaround, you can directly use the file directive in CLC:
https://www.flatcar.org/docs/latest/setup/releases/update-strategies/#disable-automatic-updates
In the example you would replace SERVER=disabled with GROUP=mygroup.

Edit: Ah, the lines

update:
  group: testgroup

are the config you used but the whitespace didn't get displayed.

[pothos]

Yes, thanks for reporting, the update: group: directive doesn't allow custom group names 🙀:
https://github.com/flatcar-linux/container-linux-config-transpiler/blob/flatcar-master/config/types/update.go#L51

The spec says group (string): the update group to follow. Most users will want one of: stable, beta, alpha. which means that it's not exclusive.

[pothos]

Path forward is writing the file directly in the Butane config.