## What this PR does
Five image builds skipped the shared buildx flags in
`hack/common-envs.mk` and wrote their own: flux-plunger,
kubeovn-plunger, both dashboard images, and metallb. The plungers
ignored `PLATFORM`, so on an arm64 workstation they came out as arm64
images that fail on amd64 nodes with `exec format error`. CI builds on
amd64, so it never showed. Dashboard and metallb hardcoded
`--platform=linux/amd64`; for metallb that sat next to `$(BUILDX_ARGS)`,
so setting `PLATFORM` gave buildx two platforms. All of them now build
through `$(BUILDX_ARGS)` only.
How it split: kubeovn-plunger landed two days before 9f2b98d36 moved the
other Makefiles onto `BUILDX_ARGS`, flux-plunger was copied from it, and
dashboard kept its own flags when that change touched it.
CI builds do not change. CI sets only `BUILDER`, which these targets
already honoured, and every build runner is x86-64.
One behaviour change is intentional: a local `make image` for dashboard
or metallb now follows the host architecture, like every other package.
On an arm64 machine, build for an amd64 cluster with
`PLATFORM=linux/amd64`.
A new bats test dry-runs every package image target with a probe
platform and a marker in `BUILDX_EXTRA_ARGS`. Each buildx call must
carry the marker and exactly that platform. On main it flags the five
targets above.
### Screenshots
No UI changes.
### Downstream repositories
- [x] No downstream repository is affected by this change
- [ ] [cozystack/website](https://github.com/cozystack/website) -
follow-up:
- [ ]
[cozystack/terraform-provider-cozystack](https://github.com/cozystack/terraform-provider-cozystack)
- follow-up:
- [ ]
[cozystack/ansible-cozystack](https://github.com/cozystack/ansible-cozystack)
- follow-up:
- [ ] [cozystack/ccp](https://github.com/cozystack/ccp) - follow-up:
- [ ] [cozystack/talm](https://github.com/cozystack/talm) - follow-up:
- [ ] [cozystack/cozyhr](https://github.com/cozystack/cozyhr) -
follow-up:
- [ ] [cozystack/cozy-proxy](https://github.com/cozystack/cozy-proxy) -
follow-up:
- [ ]
[cozystack/cozystack-telemetry-server](https://github.com/cozystack/cozystack-telemetry-server)
- follow-up:
- [ ]
[cozystack/external-apps-example](https://github.com/cozystack/external-apps-example)
- follow-up:
- [ ] [cozystack/examples](https://github.com/cozystack/examples) -
follow-up:
- [ ] [cozystack/community](https://github.com/cozystack/community) -
follow-up:
### Release note
```release-note
fix(build): every package image build honours PLATFORM, SBOM and BUILDX_EXTRA_ARGS; local dashboard and metallb builds now follow the host architecture unless PLATFORM is set.
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Chores**
* System image builds now use shared Buildx settings for platform
selection and publishing options, while retaining their image tags,
cache settings, and metadata.
* MetalLB image builds no longer explicitly target `linux/amd64`; the
selected platform follows Buildx defaults and configuration.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Aleksei Sviridkin
2e8219fb92