[PATCH v6 0/8] System updates based on systemd-sysupdate

[Demi Marie Obenour <demiobenour@gmail.com>]

This implements updates via systemd-sysupdate.  See individual commit
messages for details.

Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
---
Changes in v6:
- Remove build system changes that are not needed by the updater.
- Rely on Alyssa's patches for partition size control.
- Minor changes to individual patches.
- Drop link to patchset that has already been applied.
- Link to v5: https://spectrum-os.org/lists/archives/spectrum-devel/20251126-updates-v5-0-fd746748febd@gmail.com

Changes in v5:
- Fix broken shell.nix files in intermediate patches.
- See individual patches messages for more details.
- Link to v4: https://spectrum-os.org/lists/archives/spectrum-devel/20251121-updates-v4-0-d4561c42776e@gmail.com

Changes in v4:
- Fix build errors in intermediate patches.
- Apply suggestions from code review.
- Link to v3: https://spectrum-os.org/lists/archives/spectrum-devel/20251119-updates-v3-0-b88a99915509@gmail.com

Changes in v3:
- See individual commits for details.  There are too many to mention
  here.
- Link to v2: https://spectrum-os.org/lists/archives/spectrum-devel/20251112-updates-v2-0-88d96bf81b79@gmail.com

Changes in v2:
- updates-dir-check:
  - Do not check that there is a SHA256SUMS or SHA256SUMS.gpg file in the
    update directory.  systemd-sysupdate will fail if it cannot find a
    manifest or its signature.
  - Follow symlinks in opening the directory.  The path is from a
    trusted source and will always point to a BTRFS snapshot, never a
    symlink.  The only exception is the last component, which is still
    checked to not be a symlink.
- VM:
  - Link SHA256SUMS.sha256.asc to SHA256SUMS.gpg.  Recent
    systemd-sysupdate seems to use the former name.
  - Get update URL from host.
  - Use an execline script instead of a shell script.
- Update script:
  - Unmount shared directory if already mounted.  This avoids errors
    when mounting it again.
  - Delete old snapshot if present.
  - Provide the VM information with a different directory layout.
  - Do not bind-mount the information passed into the VM into the shared
    VM folder.  Instead rely on this folder being read-only to the
    guest.  This is enforced by a read-only bind mount in virtiofs's
    mount namespace.
- Testing:
  - Lots of manual update testing.
  - Disable the test for the live image as it doesn't work anymore.
- Nix:
  - Move validation to a separate low-priority patch.
- Documentation:
  - Document that updating the system is now possible.
- Installer:
  - Remove the "Try Spectrum" button.

- Link to v1: https://spectrum-os.org/lists/archives/spectrum-devel/20251029-updates-v1-0-401c1be2a11b@gmail.com

---
Demi Marie Obenour (8):
      tools: Add directory checker for updates
      release: Compress installation images and remove live image
      Use OS version to set partition labels and UKI name
      Add B partitions to installation images
      release: Create directory with system update
      Support updates via systemd-sysupdate
      Documentation: Update support
      Validate configuration parameters

 Documentation/development/build-configuration.adoc |  15 +++
 Documentation/development/index.adoc               |   2 +
 Documentation/development/updates.adoc             |  42 +++++++
 Documentation/development/uuid-reference.adoc      |   8 ++
 Documentation/installation/getting-spectrum.adoc   |  44 ++++---
 Documentation/installation/index.adoc              |   6 +-
 host/initramfs/Makefile                            |  12 +-
 host/initramfs/etc/probe                           |  20 ---
 host/initramfs/shell.nix                           |   2 +
 host/rootfs/Makefile                               |  21 +++-
 host/rootfs/default.nix                            |  21 +++-
 host/rootfs/file-list.mk                           |   7 ++
 host/rootfs/image/etc/fstab                        |   1 +
 .../image/etc/sysupdate.d/50-verity.transfer       |  20 +++
 host/rootfs/image/etc/sysupdate.d/60-root.transfer |  20 +++
 .../image/etc/sysupdate.d/70-kernel.transfer       |  20 +++
 .../image/etc/vm-sysupdate.d/50-verity.transfer    |  18 +++
 .../image/etc/vm-sysupdate.d/60-root.transfer      |  18 +++
 .../image/etc/vm-sysupdate.d/70-kernel.transfer    |  18 +++
 host/rootfs/image/usr/bin/spectrum-update          |  87 +++++++++++++
 host/rootfs/os-release.in                          |  15 +++
 host/rootfs/shell.nix                              |   2 +
 lib/config.default.nix                             |   3 +
 lib/config.nix                                     |  27 ++++-
 lib/fake-update-signing-key.gpg                    |   3 +
 release.nix                                        |   2 +
 release/checks/integration/meson.build             |   2 +-
 release/checks/integration/try.c                   |  29 -----
 release/combined/eosimages.nix                     |   8 +-
 release/combined/grub.cfg.in                       |   5 -
 release/installer/run-vm.nix                       |   2 +-
 release/live/Makefile                              |   8 +-
 release/live/default.nix                           |   3 +
 release/live/shell.nix                             |   4 +-
 release/update.nix                                 |  33 +++++
 tools/default.nix                                  |   1 +
 tools/meson.build                                  |   4 +
 tools/updates-dir-check.c                          | 134 +++++++++++++++++++++
 vm/app/systemd-sysupdate/default.nix               |  26 ++++
 vm/app/systemd-sysupdate/download-update           |  68 +++++++++++
 40 files changed, 681 insertions(+), 100 deletions(-)
---
base-commit: d76e9b29aea9f31238d07e21db50d3fe6a80da5a
change-id: 20250928-updates-92e99849e231
prerequisite-patch-id: 930207e73dcd127b5288db63b7e6e1a9cded1d1a
prerequisite-patch-id: 85ec04609f9a90ee9ad21d743655386fe39cfd5e

-- 
Sincerely,
Demi Marie Obenour (she/her/hers)