Build hybrid image

[Lyndon-Li]

Fix issue #8415, implement multi-arch build and Windows build

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.02%. Comparing base (04d6c79) to head (bcba234).
Report is 15 commits behind head on main.

Additional details and impacted files

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##             main    #8476   +/-   ##
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  Coverage   59.02%   59.02%           
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  Files         369      369           
  Lines       39056    39056           
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  Hits        23052    23052           
  Misses      14542    14542           
  Partials     1462     1462           

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[Lyndon-Li]

At present, CI E2E supports Linux only, opened a separate issue #8477 for requirements of running it in Windows.

[kaovilai]

I had to use following to run

BUILDX_OSVERSION=ltsc2025 BUILDX_ARCH=amd64 make container-windows

We should add overridable ?= default to Makefile.

Also I thought we are also moving away from BUILDX_ to BUILD_? per last comment in design?

[Lyndon-Li]

I had to use following to run

BUILDX_OSVERSION=ltsc2025 BUILDX_ARCH=amd64 make container-windows

We should add overridable ?= default to Makefile.

No, if you want to build Windows image only, the command is BUILD_OUTPUT_TYPE=registry REGISTRY=xxx BUILD_OS=windows make container.
And we already have default values for all the input parameters, merely, the default values are not for building a Windows image. Check the Sample section in the design for details.

Also I thought we are also moving away from BUILDX_ to BUILD_? per last comment in design?

The latest code in this PR has changed to BUILD_, please double check

[kaovilai]

This overrides my current buildx builder settings. ie. I already have a kubernetes docker builder I intended to use on a more powerful system.

Can we do it in currently available builders that our docker is already set to use?

I think this can be doc as a pre-step. It is also not compatible with podman for example.

~/git/velero build-hybrid-image 1m 44s
❯ podman buildx ls
Error: unrecognized command `podman buildx ls`
Try 'podman buildx --help' for more information

~/git/velero build-hybrid-image
❯ podman buildx rm
Error: unrecognized command `podman buildx rm`
Try 'podman buildx --help' for more information

~/git/velero build-hybrid-image
❯ podman buildx create
Error: unrecognized command `podman buildx create`
Try 'podman buildx --help' for more information

[kaovilai]

BUILD_OUTPUT_TYPE=registry REGISTRY=xxx BUILD_OS=windows make container

other than that this did build.

[Lyndon-Li]

I have modified the code to accept specified buildx instance by BUILDX_INSTANCE input parameter.

[Lyndon-Li]

For the podman part, as far as my understanding, there is no conclusions/actions to support podman emulated docker purposefully. Looks like the current Makefile works, it may be a coincidence.
Anyway, with BUILDX_INSTANCE input parameter set, we don't add any new docker buildx call, hopefully this could ensure podman still work as is.
However, supporting podman is not something must-have with/without this PR. If podman is required after our evaluation, there should be separate issue and PR for the necessary changes based on this PR.

[Lyndon-Li]

For the doc part, there is a separate issue for build-from-source doc changes related to Windows support #8475, so there will be a separate PR for the same which will include the changes mentioned here.