Design the final Docker stage for filesystem export

Bottom line: Decide which files should leave the build before selecting a local output directory. Keep the final-stage contents and expected artifact list together so an export does not become an unexplained copy of everything left in that stage.

Source fact: documented behavior

The Export binaries documentation is the primary reference.

A filesystem path supplied through --output uses the local exporter to export the final build-container contents to the host location. The worked example copies its compiled binary into a scratch final stage before exporting that stage to the working directory.

What the source does not establish

This article concerns the artifact boundary of the documented export. It does not establish that an arbitrary executable runs on the host or that every compiler produces the desired target. Source-code licensing, release signing, runtime dependencies and application acceptance need their own requirements.

Applicability questions

• What exact files should the build deliver outside the container?
• Which stage supplies the final export contents?
• What output directory is approved for the exercise?
• Which separate check will establish target and application suitability?

DSE recommendation: review the exported set as a deliverable

DSE recommends writing the intended artifact list before editing the Dockerfile. Name the executable and any deliberately included supporting files. Identify which files are development inputs, intermediate outputs or release deliverables so their disposition is a conscious choice.

Follow the tutorial’s separation between the compilation stage and a minimal final stage. Review the copy instructions that cross that boundary. Keep temporary build material out of the intended deliverable unless the release requirement explicitly includes it. Use a nonsensitive local example while learning the exporter workflow.

Select a dedicated disposable output directory for the first exercise and record it with the invocation. Review the literal --output destination before running the build. Keep host-file handling separate from permission to build an image; do not point an exploratory export at an active application directory or an unreviewed collection of valuable files.

Reconcile the output as a set. Compare filenames and contents with the written artifact list, including unexpected additions. Preserve the source revision and final-stage definition with the comparison so a later packaging change can be reviewed against the same boundary. Resolve target-runtime suitability through the application procedure instead of treating the presence of a file as acceptance.

Verification and evidence

Proposed verification, not performed: use the documented small binary example in an approved lab. Record the expected final-stage file list, export into a dedicated empty test directory and collect the actual output inventory. Mark the tutorial’s example output separately from observations produced by the exercise.

For a second case, deliberately include a harmless marker file in the final stage and repeat into another approved empty directory. Compare the resulting file set with the changed stage definition and the documented export rule. Retain the Dockerfile, invocation, source revision, output inventory and discrepancy decisions. Any execution of the exported binary must have its own reviewed target and expected application result.

Official references

• Export binaries — Docker Docs.

Source review completed October 28, 2026. Recheck the official documentation and deployment-specific applicability before a production change.