or you pretend to include it as part of the ISO, so you could eventually have different ISOs from the same registration end point with different setup.

The main idea to customize partitions in elemental is that you should provide a

config.yaml

file for the elemental client to configure the installation. IMHO the simplest way to go is to include this information in a SeedImage resource so this is just part of the ISO and not part of the registration end point.

See the docs here https://deploy-preview-176--elemental-docs-staging.netlify.app/customizing#custom-elemental-client-configuration-file This describes the yaml file that should be included within the ISO. In order to keep all the setup declarative and inside k8s you can use the cloud-config field of the SeedImage resource and in that cloud-config data (which will be executed at ISO boot) you can instruct to create the

config.yaml

used by the elemental client to install with custom partitioning.

So as part of the SeedImage cloud-config field you could consider something like:

cloud-config:
  write_files:
    - content: |
        install:
          extra-partitions:
            - size: 1024
              fs: ext4
              label: EXTRA_PART
      path: /run/initramfs/live/elemental/config.yaml

I have not tested it myself yet. If I have time I will today or tomorrow. But in any case it has to be something really close to that assuming I missed some detail now.

@victorious-dog-81595 I did a test yesterday about this and noted a couple of details. The cloud-config field in seed image should be:

cloud-config:
  write_files:
    - content: |
        install:
          extra-partitions:
            - size: 1024
              fs: ext4
              label: EXTRA_PART
      path: /etc/elemental/config.yaml

And the MachineRegistration associated to this SeedImage should also include the parameter:

spec:
  config:
    elemental:
      config-dir: "/etc/elemental"

The above will create an extra partition before the default persistent partition.