[nova] Spawning instance that will do PXE booting

Thomas Goirand zigo at debian.org
Mon Dec 6 10:28:00 UTC 2021

Hi Sean,

Thanks a lot for all of your valuable info.

On 12/6/21 9:15 AM, Sean Mooney wrote:
> disbaling port security really shoudl only be required if you want to run your own dhcp server

This really is what I would like to do indeed.

> you do not nesssiasarly need to use an ipxe boot image to pxeboot either as the seabios image, depening on your host useually has pxe supprot built in.

Right, but by default, OpenStack will not do "-boot n" to make the BIOS
do PXE. So booting the ipxe.iso image is what I found as the most easy
way. Is there another way?

> your milage will vary however as this is outside the bounds of what is intended to work so if you encounterd issues adressing those would be new feature blueprint
> not bugs so they would not be backportable.

Well, my only concern is if I must disable port security (because this
needs admin credentials), though it should be possible to workaround
this using "opensack port set --allowed-address" as a non-admin.

> if your intent is to just use this for testing then following in the path of tripleo and ironic by using virtualbmc to provide ipmi access to the vm might be ok but that assuems you are deploying an
> openstack cloud which you can then ssh into the hosts to install an run the virtual bmc.

Instead of the virtual BMC which I didn't like much, I currently use
ipmi_sim from openipmi. This feels the right choice. Maybe supporting it
would be a nice addition to OpenStack.

> if you really want to do this in an unaltered cloud we would nee to configre the vm to boot form the network
> https://libvirt.org/formatdomain.html#bios-bootloader
> https://libvirt.org/formatdomain.html#specifying-boot-order
> im not sure what the best way to extend nova to support that would be, likely a neutron extention to mark ports a bootable which nova would read and then use to update the xml.
> host config is not really an option as it would be problematic for move operations, but flavor extra specs or image properites would be viable alternitive to the neutron approch.
> although neutorn ports would give a better ux.
> if you dont make progress with other approchs then you should consider fileing a spec for network boot support in nova/neutron.

Ok, thanks for your advice.

I'll try first with the ipxe.iso image, as this looks like the most easy
path for the moment, and I'll see if later on I need more.


Thomas Goirand (zigo)

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