Instance pools should have a hybrid mode between on-demand and spot
Currently instance pools can either be set to all on-demand or all spot instances.
I would like the ability to have my job clusters/interactive clusters be able to choose to have on-demand instances for driver nodes and a set number of workers and then have the remaining workers be spot instances.
I cannot currently set my driver nodes to be on-demand and my worker nodes to be spot when accessing them from a pool.
If I use an interactive cluster I can (must?) set my driver node to be on-demand and my worker nodes to be spot.