Support multiple build contexts in x-bake

[ciaranmcnulty]

I can't see any way to do this in the docs / compose-test.go

[ciaranmcnulty]

I guess this is maybe something compose should implement? I've opened a ticket there but an interim x-bake solution would be excellent

[basicdays]

Just ran into this too. The x-bake extension handles a bunch of other bake related config parameters, but the docs seems to be missing this one.

Not sure how long docker/compose#9461 will take, so at least having a way to pass through values from the compose file to the build would be extremely helpful.

The way the announcement on the Docker blog was worded, I would have expected Docker Compose files under bake to also support multiple build contexts. See wording under heading "Named Contexts in buildx bake" at the blog post.

Currently working around this by duplicating build configs in an hcl file.