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What Is a Deterministic Build?

A deterministic build is one whose output depends only on its inputs, so repeating it with identical inputs yields identical output. Achieving it means eliminating sources of nondeterminism such as embedded build timestamps, nondeterministic file ordering, absolute paths, and uncontrolled parallelism. Determinism is what makes caching and verification trustworthy.

Why it matters

If a build varies run to run, a cache cannot safely reuse its output and a reproducible-build verification will fail even on honest builds. Determinism is the practical property that lets build caches, incremental builds, and provenance checks all be relied upon.

Related concepts

  • Prerequisite for reproducible builds and safe caching
  • Remove timestamps, path, and ordering nondeterminism
  • Closely tied to hermetic builds

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