install-compile-source.md: hint at SOURCE_DATE_EPOCH
The `bazel` binary embeds a time stamp to indicate when it was
build. This is useful information in general, but makes the binary
not byte-for-byte reproducible. To overcome this problem, bazel
honors the environment variable SOURCE_DATE_EPOCH. Mention this
fact for the benefit of users packaging bazel, as reproducibility
is becoming a more and more important property of packages.
Change-Id: If983dfe977c5ed682d4efdb819c3a587dfbbe5c1
PiperOrigin-RevId: 234596785
diff --git a/site/docs/install-compile-source.md b/site/docs/install-compile-source.md
index 1f8b08b..9fd1a3b 100644
--- a/site/docs/install-compile-source.md
+++ b/site/docs/install-compile-source.md
@@ -98,6 +98,10 @@
in-place. For convenience we recommend copying this binary to a directory that's
on your `PATH` (such as `/usr/local/bin` on Linux).
+To build the `bazel` binary in a reproducible way, also set
+[`SOURCE_DATE_EPOCH`](https://reproducible-builds.org/specs/source-date-epoch/)
+in the `compile.sh` step.
+
<h3 id="bootstrap-windows">2. Bootstrap Bazel on Windows</h3>
([Scroll up](#bootstrap-unix) for instructions for Linux, macOS, and other
