Comment 8 for bug 1307614

The feature that I would like in maas to address this is the ability for the user to provide "installer config" (in addition to user-data). This installer config would be passed wholesale through maas to curtin (or d-i). .

This would allow either
a.) the user to provide curtin-config without modifying maas templates (since they can't change those unles they're admin)
b.) juju to provide curtin-config to set a certain layout of disks for its known use case.