Add support for specifying vmdk subformat when building vmdk format

[rioM1]

Currently, it looks like bootc-image-builder is locked into building streamOptimized subformat for vmdk, which would normally be fine if the use cases are restricted to vSphere and such.
However, VMWare Workstation has a long-standing bug (10+ years counting) with running streamOptimized disks on certain systems. On boot, the affected system reports a write error when loading the disk.
In these cases, the vmdk file needs to be converted to one of the following subformats: monolithicSparse, twoGbMaxExtentSparse, and monolithicFlat.

Also, as an aside, I see that there is a way to generate a manifest using bootc-image-builder manifest but I don't see a document on how to continue the build on the generated manifest using bootc-image-builder (like described in osbuild doc) ?
Until the enhancement is implemented, I was planning on manually modify the generated manifest to use monolithicSparse instead of streamOptimized subformat and run the disk build in 2 steps.

[achilleas-k]

I'm familiar with this issue and internally we're able to build both, so this should be a trivial change. I'll add it to the plan.

Also, as an aside, I see that there is a way to generate a manifest using bootc-image-builder manifest but I don't see a document on how to continue the build on the generated manifest using bootc-image-builder (like described in osbuild doc) ?

It's not entirely straightforward and generating a manifest is more of a development and debugging tool right now. If you want to try it out though, it would look a bit like this:

podman run <all the usual options> \
  -v ./manifest.json:/manifest.json \
  -v ./output:/output \
  --entrypoint /usr/bin/osbuild \
  bootc-image-builder:latest \
  --export vmdk \
  --output-directory /output \
  /manifest.json

The --export option controls which pipeline in the manifest is exported, so it needs to match the name of the pipeline that creates the vmdk image.

[rioM1]

Thanks for the quick reply.
Looks like osbuild on the manifest works fine on Linux but not podman desktop on Windows.
In any case, my original query is answered.

[achilleas-k]

https://issues.redhat.com/browse/HMS-9675