Update builder-shim to 0.6.3 for metadata only Dockerfile support by realrajaryan · Pull Request #825

Update builder-shim to 0.6.3 for metadata only Dockerfile support by realrajaryan · Pull Request #825 · apple/container

Fixes [Bug]: "Error: unknown (2): failed to solve: no build directives" on environment-only container-file build (0.5.0) #736.

Type of Change

Bug fix
New feature
Breaking change
Documentation update

Motivation and Context

BuildKit returns nil ref for Dockerfiles containing only metadata (ENV/ARG/LABEL) directives without filesystem operations (RUN/COPY/ADD). Previously, this caused builds to fail with "no build directives" error.

Builder-shim 0.6.3 fixes this by creating a minimal marker layer when ref is nil but image config is valid, satisfying OCI manifest requirements.

Also, added some tests for this behavior.

Testing

Tested locally
Added/updated tests
Added/updated docs