[RFE] Support boot to ramdisk image as a deployment method

[Stig Telfer]

The use case of Ironic can hit limitations for large-scale HPC infrastructure. Sometimes these systems can be specialised/economised to the point where they are diskless. Sometimes they skip deployment to local disk in favour of booting from a common, read-only network filesystem. Some highly-custom systems will boot to a ramdisk image. Once deployment is complete, this has advantages in the improving deterministic behaviour of a large parallel system. For some use cases, the inconvenience of a confined ramdisk environment is outweighed by the advantages.

This enhancement is requested to meet a use case shared by some members of the Scientific SIG.

[Dmitry Tantsur (divius)]

I like the idea, but I have a feeling it will need a spec.

[Tim Randles (trandles)]

Boot-to-ramdisk is a critical need for the HPC use case. I'm happy to write up the spec. What level of detail is required for a spec? Is there an example you can point me to for guidance?