Tripleo needs to support full overcloud disk images

[Yolanda Robla]

Description of problem:

Currently openstack image upload from tripleo, needs that 3 images are passed:
overcloud-full.qcow2
overcloud-full.initrd
overcloud-full.vmlinuz

But there can be another use case, that is supported in Ironic, and that is the ability to use full disk images, as documented on:

http://docs.openstack.org/project-install-guide/baremetal/draft/configure-integration.html#configure-the-image-service

Currently if you just provide the qcow2 image, the command fails complaining about missing initrd and vmlinuz.

Expected results:

tripleo shall just upload qcow2, and do not set kernel_id and ramdisk_id images, allowing for ironic to consider it as a full disk image.

[Dmitry Tantsur (divius)]

Important note: a whole disk image is not the same qcow2 image that we use. It is expected to have the whole partitioning built-in. When using DIB, you need to use "vm" element instead of "baremetal".

[Yolanda Robla (yolanda.robla)]

So talking from my experience, the steps needed to allow full disk images is:
1. Provide a new way of building images inside tripleo. Currentl, this basically needs to use vm (or other custom element) instead of baremetal element, in diskimage-builder config. Please not that this effort https://review.openstack.org/#/c/375261/ is also related.
2. Update TripleO "openstack image upload" call, to don't require overcloud-full.initrd and vmlinuz files, in the case of full disk images. If that's the case, no kernel and initrd flags need to be added as glance properties on overcloud-full.qcow2
3. Ensure that ironic supports iscsi deployment correctly. Currently this change is needed: https://review.openstack.org/381893