BuildKit local and tar exporters accept src

Introduced 2026-10-07 · score 0.96

HOW TO USE IT

When exporting a build result with the local or tar exporter, set `src` to the subdirectory to export; it must point to a directory within the build result.

WHY THIS HELPS

Export a selected subdirectory from a build result with the local or tar exporter.

REQUIREMENTS AND LIMITATIONS

• Version: v0.34.0
• --output type=local (required): Select the local exporter; `dest` names its destination directory.
• --output type=tar (required): Select the tar exporter; `dest` names its tarball destination. Tar output may also be sent to stdout.
• src: Exporter option: path to a directory in the build result. It is resolved from the result root; relative and absolute forms are equivalent. Its contents go to the destination root. Omitting it exports the entire filesystem.
• dest: Exporter option: destination directory or tarball path. The documented tar example also supports stdout without `dest`.
• Prerequisite: Use a BuildKit daemon that supports `src`; older daemons may ignore the option and export the entire build result.
• The `src` option applies to local and tar exporters.

FIRST-PARTY EVIDENCE

• https://github.com/moby/buildkit/releases/tag/v0.34.0
• https://github.com/moby/buildkit/blob/v0.34.0/README.md

Check the installed version and the source before using it. Entry JSON

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