Fighting Game · Guides & deep dives

V2 Reproducible Builds

A guides & deep dives document in the Fighting Game library.

0sections1 minread
Markdown source
On this page

V2/ue/Tools/plan-v2-reproducible-builds.py expands V2/ue/Build/Reproducible/v2-reproducible-builds.json into two build passes for every release-critical artifact. The contract fixes the timestamp and locale with SOURCE_DATE_EPOCH=1781740800, TZ=UTC, LC_ALL=C.UTF-8, and LANG=C.UTF-8, disables incremental Rust output with CARGO_INCREMENTAL=0, and remaps host paths with --remap-path-prefix=$(Workspace)=/workspace.

Rust commands run with --locked, a stable target directory per pass, and -Ccodegen-units=1. Unreal BuildGraph commands receive -Set:SourceDateEpoch=1781740800 and -Set:DeterministicBuild=1. Generated plans, such as the shader distribution plan, are treated as artifacts and hashed like binaries.

Every pass writes a normalized archive command using tar --sort=name --mtime=@1781740800 --owner=0 --group=0 --numeric-owner. The digest step uses compare-v2-reproducible-artifacts.py --write-manifest to emit a SHA-256 manifest. The comparison step reruns compare-v2-reproducible-artifacts.py against pass A and pass B manifests and fails if build.reproducible.digest_mismatch_count is nonzero.

Required gates:

  • reproducible-build-plan-generated
  • reproducible-build-digest-match
  • reproducible-build-target-coverage
  • reproducible-build-source-date-epoch

The release evidence path is $(ArchiveRoot)/Reproducible/reproducible-build-plan.json. The CI validator is:

bash
python3 V2/ue/Tools/check-v2-reproducible-builds.py