Friday 12 May 2023

Re: NBS removals of old kernels from stable -security and -updates pockets

Confirming publicly that there has been an exception made for future gke and gkeop (Anthos on VMware) kernel header and module packages due to the GKE deployments being long-lived and often having older kernels installed.

This issue with GKE specifically was reported publicly @ https://lists.ubuntu.com/archives/kernel-team/2023-May/139318.html

Phil

On Fri, 12 May 2023 at 13:20, Juerg Haefliger <juerg.haefliger@canonical.com> wrote:
On Tue, 25 Apr 2023 11:05:39 +0200
Steve Langasek <steve.langasek@ubuntu.com> wrote:

> Hi folks,
>
> Kernel updates have an interesting property that, unlike most SRUs, the
> binary package names change for each update, because the ABI is presumed to
> change each time.
>
> The result of this is that each kernel update causes the binary packages
> from the previous version to become "NBS" (not built from source).
>
> Cleanup of NBS packages from the archive is a manual process involving
> Archive Admins; they are not automatically removed from the archive.  And
> historically, we did not want to remove NBS kernel packages during a release
> cycle, because our netboot images relied on modules of matching ABI being
> available in the archive corresponding to the kernel ABI used in the netboot
> image - and as we did not control when our users deployed netboot images on
> their infrastructure, we did not want to arbitrarily break working customer
> systems, we did not remove NBS kernel packages as we went - only at EOL of a
> release.
>
> However, netboot images that rely on kernel packages of a matching ABI being
> available in the archive are an artifact of debian-installer, and as of
> jammy, we no longer ship debian-installer.  Therefore, this rationale for
> retaining the old kernel binary packages in the archive no longer exists.
>
> Nearly 50% of all binary packages published in the jammy-updates pocket
> today are from kernels[1], and this proportion only increases as an LTS
> ages.  I have not done the analysis, but I expect the kernel packages to
> represent a similar or higher proportion of the *size* of the -updates
> pocket.  Thus, keeping these old binary packages around impacts both the
> speed of `apt update` for both -updates and -security pockets, and the size
> of the mirror set for these releases.
>
> I am therefore intending that, for jammy and later releases, we start to
> prune NBS kernel packages on an ongoing basis, not just at EOL time.
>

We already have users complaining on IRC about missing kernel packages...
What is the official way/process for getting older packages for example for
crash dump analysis where one might need an older kernel+dbgsym from an
active series?

...Juerg
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Phil Roche
Staff Software Engineer
Canonical Public Cloud