feat: Allow import/usage of local container image

[mynetz]

I would like to use custom local container images in an offline build. Either via the Dockerfile feature or another way to prevent FWA (or Dagger) to query an online resource.

While the Dockerfile can be used directly in a FWA build, and works fine. There is no way to then to do something that is equivalent to "offline usage" as described for public containers in: https://9elements.github.io/firmware-action/firmware-action/offline_usage.html

It would be great to have the option to provide either a reference in the local Docker cache or a container image. Eg. "sdk_url": "container_image.tar" or "sdk_url": "<my_local_label>:<tag>@sha256:...."

Note: It seems there is a development in dagger that might bring something similar as a generic option to dagger.

• ✨ Import image from local container runtime dagger/dagger#10737
• feat: add host.containerImage to import containers from the host dagger/dagger#10810

It may take some time though.

[AtomicFS]

The use-case is to use completely air-gapped computer that is never connected to the internet.

The current offline feature is more tailored to occasional offline usage.

[mynetz]

In case this is a question: Yes.

In fact it is a use-case that does not speculate on the offline/air-gaped environment and would like to have it localized to the checkout/download.

It may be fair to speculate that a true air-gaped solution may have a local registry, but that would probably required some path mangling or changes to the FWA config. Which would also be not optimal.