bake: only validate build property in compose file services

[crazy-max]

relates to:

• Unable build docker-compose file with advanced network configuration #612
• bake does not support compose profiles #718
• Additional property name is not allowed #1106
• Bake does not allow or use tags from docker-compose.yml #1187
• buildx bake file doesn't support new ulimit directives #2241
• cgroup property is not allowed when using bake command with docker compose as input #2548

When new properties are added to the compose spec, Bake might fail to build them as the validation is not yet aware of them unless the compose-go dependency is updated and a new release of Buildx made. We should just validate the build property that is the only part we are using with bake to prevent such issues.

@ndeloof @glours Would it be possible to have an option in the loader to just validate specific properties?:

buildx/bake/compose.go

Lines 44 to 52 in 758ea75

	}, func(options *loader.Options) {
	projectName := "bake"
	if v, ok := envs[consts.ComposeProjectName]; ok && v != "" {
	projectName = v
	}
	options.SetProjectName(projectName, false)
	options.SkipNormalization = true
	options.Profiles = []string{"*"}
	})

Maybe smth like ValidateBuildOnly or SkipUnknown?

[ndeloof]

Validation is based on JSON schema so can't be applied on a subset AFAICT
Maybe an option is for bake to load Model (loadModelWithContext) with validation disabled, then remove everything from the tree that isn't a service.build or reference supported by bake, Validate and eventually Transform model into a Project

What about stepping down compose.yaml support in bake, so bake doesn't manage override/include/interpolation crazyness but just consumes a "canonical" compose.yaml file, produced by docker compose config ?

[crazy-max]

Maybe an option is for bake to load Model (loadModelWithContext) with validation disabled, then remove everything from the tree that isn't a service.build or reference supported by bake, Validate and eventually Transform model into a Project

That would work but would need modelToProject to be public: https://github.com/compose-spec/compose-go/blob/3dcedcb8301327e5f3a97eb34dfa65a8fe205726/loader/loader.go#L561. Is that ok?

What about stepping down compose.yaml support in bake, so bake doesn't manage override/include/interpolation crazyness but just consumes a "canonical" compose.yaml file, produced by docker compose config ?

Meaning something like docker compose config | docker buildx bake ?

[crazy-max]

Opened compose-spec/compose-go#805 if that SGTY.

[ndeloof]

Meaning something like docker compose config | docker buildx bake ?

yes indeed, or maybe bake could shell-out to get compose file parsed/merged/interpolated/overridden/enable profiles/xxx without the need to worry about the many supported supported syntaxes, then map canonical yaml to go structs with only support for the build section