Please provide installer kernel and initrd from daily-live images as separate download for netbooting

[Frank Heimes]

If someone is going to do a netboot installation with subiquity, which is the new default installer for _all_ architectures starting with 20.04 (for some already earlier), one of the first things needed is to download the installer kernel and initrd.

In the past 'd-i days' people went to:
http://ports.ubuntu.com/dists/xenial-proposed/main/installer-$(arch)/
and downloaded just the kernel and initrd from there.
(and hopefully validated their download with the checksums ...)

Now with subiquity one has to download the entire daily-live ISO, just to extract kernel and initrd (taking it from the casper folder of the ISO) and use it to start (net-)booting.
In a further (early installation) step the daily-live ISO is then downloaded again and finally subiquity started.
Hence the daily-live ISO is downloaded twice!
That's btw. the same for all architectures, even if the netboot process is a bit different.
See exemplarily the sequence of steps for amd64:
https://discourse.ubuntu.com/t/netbooting-the-live-server-installer/14510
and ppc64el:
https://discourse.ubuntu.com/t/netbooting-the-live-server-installer-on-power-ppc64el-with-petitboot/15348
(but again, the same also for arm64 etc.)

Since this is a waste of resources it would be best if the daily-live kernel and initrd can be made available as separate downloads, too (incl. checksums) - knowing that things are a bit more strict here, since the kernel and initrd needs to fit exactly to the ISO that is used later.
Anyway, still doable by mentioning/using the timestamp in the kernel/initrd download folder or have it as part of the URL.

[Frank Heimes (fheimes)]

Please let me add that the directory structure of the daily-live installation kernel and initrd should be compatible to "virt-install --location"'s distribution tree installations.
Some snippets form the man page:
      -l, --location OPTIONS
           Distribution tree installation source. virt-install can recognize
           certain distribution trees and fetches a bootable kernel/initrd
           pair to launch the install.
...
           Some distro specific url samples:
...
           Debian
               https://ftp.us.debian.org/debian/dists/stable/main/installer-amd64/
           Ubuntu
               https://us.archive.ubuntu.com/ubuntu/dists/wily/main/installer-amd64/

Please notice that using --cdrom is not a valid alternative to --location, since --extra-args for kernel arguments is only supported in combination with --location.

With the change of the URL from:
http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/images/
to
http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/
virt-install is currently broken on Ubuntu (for all architectures), since virt-install looks for .../images/
(see also LP 1872941)

With a proper location and layout for the daily-live installer artifacts virt-install could be made operational again, which is highly desirable, since it's a popular tool used by partners and customers (even if it's in universe).
And almost all other distros support it too (see man page), so we should not fall behind ...

[Dimitri John Ledkov (xnox)]

Please do not mix separate issues.

Unpacked subiquity artefacts are not d-i compatible and will not be virt-install compatible. Unless virt-install grows support for these new unpacked subiquity artefacts - but it should not! because it should use unpacked cloud-images instead.

If your only ask for unpacked artefacts is due to virt-install not working, then this bug is invalid.

If this ask is for unpacked artefacts and has other non-virt-install use cases, we can discuss it further.

[Frank Heimes (fheimes)]

Well, I do not _mix_ two separate issues, but I try to find synergies.
My hope was that if kernel/initrd is hosted in a proper way, it will not only help for people doing netboot installs (this ticket is mainly about this, as one can read in bug description), but maybe also for people using virt-install.
(I'm still thinking about a way to get virt-install, which is currently broken for focal, fixed again - the main conversation about this should be of course at LP 1872941.)

[lerxst (lerxst)]

Although this bug was submitted to have the unpacked kernel & initrd images made available separately, I am not even able to successfully netboot using the images extracted from the live-installer ISO (latest daily build from 4/17). I'm following the instructions from the URL in the bug description and specifying ip=dhcp & url=... kernel parameters but it continues to look for the installer components in the cd-rom (Can't open /dev/sr0: No medium found) and drops into an initramfs shell.

[dann frazier (dannf)]

@lerxst - please report a separate bug for that, and keep this bug focused on the kernel/initrd availability.

[Zippy Zebu (zippy.zebu)]

@Dimitri

Someone pointed me to this bug.

Why does the netboot image (amd64)has to do any of this ? http://cdimage.ubuntu.com/netboot/focal/ page shows that server guide page instead of actual netboot image page like in eoan (http://cdimage.ubuntu.com/netboot/eoan/). LP: #1875497

Please stop changing netboot location every month. This is third time I filed a bug about not able to find netboot image inside past two months. We build our iso from netboot image. This is very inconvenient for all of us.

[lerxst (lerxst)]

@zippy.zebu

That's because the powers-that-be at Canonical have decided that ubuntu server users don't need d-i based netboot installation and have decided to discontinue it. They have hinted that these images might be removed at the next point release.