Goal

• Provide further ways for the user to customize the installation, to a level where it could replace e.g. 80% of on-prem UPI.
• This may take the form of specific configuration options, or a generic butane-based ignition override, or some combination of the two.
• There may or may not also be uses for overriding kernel arguments and/or the agent ISO's ignition.

Why is this important?

• For on-premises deployments, the agent installer provides a much better experience than UPI while placing fewer demands on the user's environment than IPI. However, users will continue to be forced into UPI if the customizations they need to apply cannot be configured through the agent installer.

Scenarios

The following customizations have been identified as useful to users (this is intended to be a running list):

1. Disk partitioning
2. Disk encryption (checkbox already exists in assisted)
3. Hardware RAID
4. oneshot systemd service to fix the serial console on baremetal

Previous Work

1. NMState-based per-host network config
2. Storage multipath (including per-host root device hints)

Open questions::

1. Do we need a generic Butane ignition override?
2. Do we need to customize the agent ISO (i.e. discovery) ignition?
3. Do we need to customize kernel arguments? (Beyond what MachineConfig already allows for)
4. Should customizations be per-host, per-role, per-cluster, or more than one of those?
5. Which features should be specified directly (rather than as ignition overrides) in agent-config.yaml?