[RFE] Allow a mechanism to override the PXE boot options for a unique image via glance properties

[Vladyslav Drok]

Fedora Atomic 21 requires the following command line to boot properly:

pxe_append_params = nofb nomodeset vga=normal console=tty1 no_timer_check rd.lvm.lv=atomicos/root root=/dev/mapper/atomicos-root ostree=/ostree/boot.0/fedora-atomic/a002a2c2e44240db614e09e82c7822322253bfcaad0226f3ff9befb9f96d315f/0

Overridding this globally is not ideal since other images may have different roots and may not want the ostree parameter. If root is specified in the override, it should replace the root in the pxe template or just override the template parameters all-together. This may require changing how blkid is used to determine the root UUID of the filesystem as well during the property override case.

[Ruby Loo (rloo)]

Specification has been approved and is available at http://specs.openstack.org/openstack/ironic-specs/specs/approved/override-pxe-options-via-glance-property.html.

Copying this from old BP (https://blueprints.launchpad.net/ironic/+spec/override-pxe-options-via-glance-property):

Gerrit topic: https://review.openstack.org/#q,topic:bp/override-pxe-options-via-glance-property,n,z

Spec: https://review.openstack.org/177859
    Override PXE options via Glance property

Addressed by: https://review.openstack.org/178229
    Override PXE kernel cmdline via Glance property

[Julia Kreger (juliaashleykreger)]

A couple items:

1) A kernel_append_params option now exists which addresses the base issue.
2) We no longer support explicitly network booting nodes by default, unless one is using the ramdisk deployment interface.

As such, I'm going to mark this fix released.