What's the correct way to write a file using the cloud-config before installation?

[AlexanderTheGrey]

What must the cloud-config include to write a file to e.g. /etc/netplan during the live ISO session before installation? None of the stages seem to persist file writes, though I can write to /etc/netplan manually after booting the ISO (before installation).

For context, I have sort of a bare-bones cloud-config that I write to /oem in the ISO, and upon boot (before installation), I can apply network settings if the file already exists in the ISO, but I can't write that network configuration file using the files section of a stage.

[jimmykarily]

Either /etc is mounted read only already or it's not mounted at all at the moment you try to write to it, I assume.
Maybe you can manually remount it rw to add your file (e.g. as we do here but for different reasons)

Have you tried kairos-install.pre or before-install stages? @Itxaka any other ideas?

[AlexanderTheGrey]

Thanks for the tips. It turns that, when I deleted the - name key in my cloud-config, I had files instead of - files, so the files key was being treated as a mapping, instead of a list of mappings.

This worked:

fs:
    - name: Test
      files:
      - path: /etc/test
        content: |
          test

This (unsurprisingly) didn't work:

fs:
    files:
    - path: /etc/test
      content: |
        test

kairos-agent validate didn't seem to catch that deviation from the YAML schema for some reason. Do you know why?

[jimmykarily]

kairos-agent validate didn't seem to catch that deviation from the YAML schema for some reason. Do you know why?

Probably because stages: is not part of the RootSchema: https://github.com/kairos-io/kairos-sdk/blob/7ef466cd9d37005e7ac6f25092df2bbc1fe3a428/schema/root_schema.go#L13

[jimmykarily]

I assume you specified fs: under stages: ? Othewise I don't see where fs: could be parsed.

[AlexanderTheGrey]

Yes, I specified fs under stages.

Should stages be part of the RootSchema, or is there some other way to validate the entire cloud-config before deployment?

[jimmykarily]

I think they should be. I created a ticket for this: #3386