What Is a Deterministic Timestamp?
A deterministic timestamp is a fixed time value, usually derived from the source such as the latest commit date, that a build embeds in place of the current wall-clock time. Because the value depends only on inputs, two builds of the same source embed the same timestamp. This removes one of the most common sources of nonreproducible output.
Why it matters
Embedding the real current time makes every build differ even when nothing in the source changed, breaking reproducibility and cache hits. Pinning the timestamp to a source-derived value keeps artifacts identical across rebuilds. The conventional way to supply that value to tools is the SOURCE_DATE_EPOCH variable.
Related guides
What Is SOURCE_DATE_EPOCH?SOURCE_DATE_EPOCH is a standard environment variable that tells build tools which fixed timestamp to embed, e…
What Is Build Reproducibility?Build reproducibility is the property that building the same source in the same environment yields a bit-for-…
What Are Vendored Dependencies?Vendored dependencies are third-party packages committed directly into a project's repository so builds do no…