Local & Hardware OTA Testing#

Load when testing bootc upgrades via a local registry — QEMU VM or physical hardware.

When NOT to Use#

• CI pipeline questions → ci.md

Overview#

Run a local zot registry → build dakota image → push to local registry → boot a VM or physical machine pointed at the local registry → run bootc upgrade.

Setup#

Start Local Registry#

# Idempotent — safe to run multiple times
just registry-start

Manual fallback:

sudo podman run -d --name egg-registry --replace \
  -p 5000:5000 \
  -v egg-registry-data:/var/lib/registry \
  ghcr.io/project-zot/zot-minimal-linux-amd64:latest

The egg-registry-data volume persists across reboots. Verify it's bound to 0.0.0.0:5000 (not just localhost):

sudo podman inspect egg-registry | grep -i hostip

Configure Insecure Registry on Test Machine#

QEMU VM — inside the VM, 10.0.2.2 is the QEMU user-mode gateway (your host machine):

sudo tee /etc/containers/registries.conf.d/50-local-dev.conf <<'EOF'
[[registry]]
location = "10.0.2.2:5000"
insecure = true
EOF

Physical hardware — use your build host's LAN IP:

sudo tee /etc/containers/registries.conf.d/50-lab-dev.conf <<'EOF'
[[registry]]
location = "<build-host-ip>:5000"
insecure = true
EOF

This drop-in persists across reboots. Leave it in place — it's harmless when the machine points at GHCR.

Build → Push → Test Loop#

# 1. Build the image
just build

# 2. Export OCI image to podman
just export

# 3. Push to local registry
just push-local localhost:5000 # QEMU path (host gateway = 10.0.2.2 from inside VM)
just push-local <build-host-ip>:5000 # Physical hardware path

# 4a. QEMU VM — boot a VM
just boot-fast # ephemeral VM via virtiofs (requires virtiofsd)
just boot-vm # standard QEMU VM with display

# 5. On the test machine — switch to local registry (first time only)
sudo bootc switch 10.0.2.2:5000/dakota:latest # QEMU
sudo bootc switch <build-host-ip>:5000/dakota:latest # Physical

# 6. Subsequent upgrades
sudo bootc upgrade
sudo systemctl reboot

Lab rule: Build host alone is not a lab result. Full loop = build → push → bootc switch on test machine → reboot → verify.

After Reboot#

bootc status # confirm new image is active
systemctl --failed # check for failed units
journalctl -p err --since boot # check for boot errors

Reverting to GHCR#

sudo bootc switch ghcr.io/projectbluefin/dakota:latest
sudo systemctl reboot

Port Conflict Fix#

If port 5000 is occupied:

sudo ss -tlnp | grep 5000
sudo podman start egg-registry

Lessons Learned#

zstd broken with bootc composefs#

Do not use --compression-format=zstd:chunked for local registry pushes. It breaks bootc switch/bootc upgrade when the image uses composefs.

# Correct
just push-local localhost:5000

# Wrong — breaks composefs
sudo podman push --compression-format=zstd:chunked localhost:5000/dakota:latest

bootc switch same-content trap#

bootc switch <tag> silently does nothing if the tag resolves to the already-booted digest. Force the upgrade with the exact digest:

DIGEST=$(curl -sI http://<zot-registry>/v2/dakota/manifests/<TAG> \
  -H 'Accept: application/vnd.oci.image.manifest.v1+json' \
  | grep -i docker-content-digest | awk '{print $2}' | tr -d '\r')
sudo bootc switch --transport registry <zot-registry>/dakota@${DIGEST}

Assertions must execute — not just check file presence#

test -f /path/to/file is not a functional test. Any recipe must be tested by executing it and checking output:

# BAD — only confirms the file exists
--assert 'installed:test -f /usr/share/ublue-os/just/default.just'

# GOOD — confirms the recipe actually runs
--assert 'recipe-runs:echo n | TERM=dumb ujust report 2>&1 | grep -qiE "Collecting"'

BST failure cache trap#

When BST caches a failed build, retrying without clearing the cache immediately fails again with [00:00:00] elapsed.

just bst artifact delete bluefin/myelement.bst
just bst build bluefin/myelement.bst

Pre-existing failures vs your changes#

Before attributing a build failure to your branch, confirm the same element fails on upstream/main:

git stash
git checkout upstream/main
just bst build bluefin/<failing-element>.bst
git checkout -
git stash pop

If it fails on upstream too, file an issue immediately and continue.

just 1.47.1 heredoc tokenizer#

just 1.47.1 aggressively tokenizes heredoc content in shebang recipes, rejecting lines starting with -, ..., $(uname -m) with flags past column 25, or (1/5/15 min).

Fix: Replace heredocs with printf '%s\n' per line and pre-compute command substitutions into variables.

ujust vs just distinction#

• just = developer build system (Justfile in repo root)
• ujust = user-facing commands in the running image (files/just-overrides/default.just)

Changes to files/just-overrides/default.just require a BST element rebuild to land in the image.