Custom Bazzite DX NVIDIA (open) image: BlueBuild recipe, GHCR workflow, cosign setup

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-29 12:05:12 -04:00
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+# main-desktop
+
+Custom [Bazzite DX](https://github.com/ublue-os/bazzite-dx) image for my desktop, built with
+[BlueBuild](https://blue-build.org), published to GHCR by GitHub Actions, and signed with cosign.
+
+- **Base:** `ghcr.io/ublue-os/bazzite-dx-nvidia` — Bazzite DX, KDE Plasma, **NVIDIA open kernel
+  modules**. There is no separate `-open` DX image anymore: DX NVIDIA is open-driver-only, which
+  is exactly what the RTX 5090 (Blackwell) requires. Current stable ships driver **610.x** (open).
+- **Pinned** to Fedora 44 via `image-version: stable-44` in
+  [recipes/recipe.yml](recipes/recipe.yml). No surprise major upgrades; bump to `stable-45`
+  deliberately.
+- **This image layers almost nothing.** The base already includes Steam and the gaming stack,
+  Flatpak, Docker CE + CLI, Podman, VS Code, Homebrew, **and nvidia-container-toolkit with
+  automatic CDI setup** (`ublue-nvctk-cdi.service` regenerates `/etc/cdi/nvidia.yaml` each boot).
+  What this recipe adds: the cosign signature-verification policy and a declarative first-boot
+  Flatpak set. That's it — by design.
+
+Why BlueBuild instead of the raw Containerfile template: with the container toolkit already
+in-image, the whole custom layer is "install these Flatpaks on first boot + trust my signature",
+which the `default-flatpaks` and `signing` modules express declaratively in ~40 lines of YAML —
+no hand-rolled first-boot systemd unit needed.
+
+## One-time setup (before first push)
+
+1. Create a GitHub repo and push this directory to it (`main` branch).
+2. Generate the signing keypair in the repo root (**press Enter for an empty password** — the
+   build action cannot use an encrypted key):
+
+   ```bash
+   cosign generate-key-pair
+   ```
+
+3. Store the private key as an Actions secret and commit only the public half:
+
+   ```bash
+   gh secret set SIGNING_SECRET < cosign.key
+   git add cosign.pub && git commit -m "Add cosign public key" && git push
+   ```
+
+   `cosign.key` is git-ignored — never commit it.
+4. The workflow (`.github/workflows/build.yml`) now builds on every push, on manual dispatch, and
+   daily at 06:00 UTC (so base-image updates flow through automatically — this is what makes the
+   image self-updating). Images publish to `ghcr.io/<your-github-user>/main-desktop`.
+5. If the GHCR package ends up private, make it public in the package settings (Packages →
+   main-desktop → Package settings → Change visibility), or rebasing will fail to pull.
+
+## Rebasing the desktop onto this image
+
+From the existing Bazzite install, rebase in two steps — first unsigned (this installs the image,
+which contains the signing policy and public key), then signed:
+
+```bash
+# Step 1: unsigned rebase, then reboot
+rpm-ostree rebase ostree-unverified-registry:ghcr.io/<your-github-user>/main-desktop:latest
+systemctl reboot
+
+# Step 2: switch to the signed ref, then reboot
+rpm-ostree rebase ostree-image-signed:docker://ghcr.io/<your-github-user>/main-desktop:latest
+systemctl reboot
+```
+
+After step 2, every update is signature-verified. `:latest` is fine here — the Fedora pin lives
+in the recipe, so `latest` never crosses a major until the recipe says so.
+
+Roll back anytime with `rpm-ostree rollback` (or pick the previous deployment in the boot menu).
+
+## Install-time checklist
+
+1. **Driver sanity:** `nvidia-smi` reports driver **≥ 580** (currently 610.x) and the RTX 5090 is
+   listed. Confirm open kernel modules: `modinfo -F license nvidia` should say `Dual MIT/GPL`
+   (the proprietary module says `NVIDIA`). Blackwell only works on the open modules.
+2. **Signature:** verify the published image against the committed public key:
+
+   ```bash
+   cosign verify --key cosign.pub ghcr.io/<your-github-user>/main-desktop:latest
+   ```
+
+3. **Deployment:** `rpm-ostree status` shows the booted deployment is
+   `ostree-image-signed:docker://ghcr.io/<your-github-user>/main-desktop` and the base version
+   matches a recent build.
+4. **Flatpaks:** the first-boot service installs the whole list below; give it a few minutes on
+   first login (it notifies when done). Check with `flatpak list --system`.
+5. **Docker group:** run `ujust dx-group` (adds you to `docker` and friends), then log out/in.
+6. **GPU in containers:** see the section below — run the one-liner test.
+
+## GPU in containers (CUDA on the 5090)
+
+`nvidia-container-toolkit` is already in the image and a boot service generates the CDI spec
+automatically. CDI is the shipped mechanism:
+
+```bash
+# Podman — works out of the box:
+podman run --rm --device nvidia.com/gpu=all docker.io/nvidia/cuda:12.8.0-base-ubuntu24.04 nvidia-smi
+
+# Docker — CDI device syntax also works on current Docker CE:
+docker run --rm --device nvidia.com/gpu=all nvidia/cuda:12.8.0-base-ubuntu24.04 nvidia-smi
+```
+
+If you want the classic `docker run --gpus all` syntax, that needs a one-time runtime hookup
+(this writes to `/etc/docker/daemon.json`, which is mutable and survives updates):
+
+```bash
+sudo nvidia-ctk runtime configure --runtime=docker
+sudo systemctl restart docker
+```
+
+## First-boot Flatpaks
+
+Installed system-wide from Flathub by the `default-flatpaks` module. All IDs verified against
+Flathub (2026-07).
+
+**Official / verified listings:** Bambu Studio, Bitwarden, Discord, Firefox, Thunderbird,
+FreeCAD, GIMP, HandBrake, LibreOffice, Moonlight, PCSX2 (`net.pcsx2.PCSX2` — the official
+build), Podman Desktop, Warzone 2100, XIVLauncher (`dev.goats.xivlauncher`).
+
+**Community / unverified listings — know what you're running:**
+
+| App | ID | Note |
+|---|---|---|
+| GitHub Desktop | `io.github.shiftey.Desktop` | Community Linux fork; the "shiftey" spelling is the real ID |
+| MakeMKV | `com.makemkv.MakeMKV` | Community packaging of the proprietary app |
+| GeForce NOW | `io.github.hmlendea.geforcenow-electron` | **Unofficial** Electron wrapper, not an NVIDIA product |
+| VLC | `org.videolan.VLC` | No verified badge on Flathub (still the VideoLAN-maintained build) |
+| Godot | `org.godotengine.Godot` | No verified badge on Flathub |
+
+**GeForce NOW on the 32:9 monitor:** the service only streams 16:9 (and some 21:9) aspect
+ratios, so expect pillarboxing at 5120x1440 — that's a service limitation, not a config problem.
+
+## Post-install steps (manual by design — don't automate these)
+
+### PIA VPN — native WireGuard, not the app
+
+The PIA desktop app installs into `/usr` and breaks on the read-only filesystem. Skip it:
+
+1. Log in at PIA's [OpenVPN config generator](https://www.privateinternetaccess.com/pages/ovpn-config-generator)
+   (or generate a WireGuard config via their API/support flow) and download configs for your
+   preferred regions.
+2. KDE **System Settings → Network → Connections → Add (+) → Import VPN connection…**, pick the
+   downloaded file, and enter your PIA credentials.
+3. This is plain NetworkManager — it lives in `/etc`, survives every update, and gets a
+   connect/disconnect toggle in the system tray.
+
+### Microsoft Teams — PWA via Edge
+
+No native Linux client. Install **Microsoft Edge specifically** (corporate conditional
+access / Intune compatibility): `flatpak install flathub com.microsoft.Edge`, sign in to
+<https://teams.microsoft.com>, then menu → **Apps → Install this site as an app**.
+
+### Claude desktop — PWA
+
+No official Linux app. Open <https://claude.ai> in Edge (or any Chromium browser) and use
+**Install this site as an app** the same way.
+
+### Proton-GE
+
+Already handled by Bazzite: use the preinstalled **ProtonUp-Qt** GUI (or browse `ujust` — run
+`ujust` with no arguments to list recipes). Don't install anything extra.
+
+## Node / toolchains — not in the image
+
+Node, npm, etc. are deliberately **not layered**. Use per-project versions instead:
+
+```bash
+brew install mise         # Homebrew ships in the base image
+mise use node@22          # per-project .mise.toml; `mise use -g node@22` for a global default
+```
+
+(Plain `brew install node` also works if you just want one global Node.)
+
+## Display note
+
+The 49" 32:9 (5120x1440) ultrawide needs nothing at the image layer. Post-install: set scale and
+refresh rate in KDE System Settings → Display; KDE's window tiling (Meta+drag, or a tiler like
+Polonium) is worth setting up at this width. VMs are remote via Remmina — there is intentionally
+no local hypervisor tooling in this image.
+
+## Maintenance
+
+- **Change the Flatpak list / packages:** edit [recipes/recipe.yml](recipes/recipe.yml), push,
+  and the next update picks it up. (Removing an app from the list does not uninstall it from the
+  machine; `flatpak uninstall` it once by hand.)
+- **Jump Fedora majors:** change `image-version: stable-44` → `stable-45` in the recipe when
+  ready, push, then update normally.
+- **Check build status:** the Actions tab; builds also run nightly, so a broken base shows up
+  there before it reaches the machine.