cosmix-lib-buildinfo — build provenance

cosmix-lib-buildinfo embeds a consumer's compile-time identity without adding runtime dependencies. It records the package and version, git revision, dirty-tree state, and build timestamp used for fleet inventory and Bus service registration.

What it is

BuildInfo contains five compile-time fields:

  • pkg and version from the crate where build_info!() expands;
  • git_sha, a 12-character revision captured from the consumer repository;
  • git_dirty, reporting uncommitted repository content at build time; and
  • build_time, an RFC3339 UTC timestamp.

BuildInfo::line() renders the standard one-line form. now_rfc3339() is the separate runtime helper used for a citizen's process start timestamp.

How consumers use it

Add the crate as both a normal dependency and a build dependency. The consumer's build.rs calls emit():

fn main() {
    cosmix_lib_buildinfo::emit();
}

The consumer then expands the macro in its own crate:

let build = cosmix_lib_buildinfo::build_info!();
println!("{}", build.line());

This two-stage arrangement is deliberate. emit() runs git in the consumer's repository and exports COSMIX_GIT_SHA, COSMIX_GIT_DIRTY, and COSMIX_BUILD_TIME; build_info!() combines them with that consumer crate's CARGO_PKG_* values. It therefore describes the binary being built, not the bus checkout that supplies the helper.

Missing git or a missing emit() call degrades provenance to unknown rather than failing the build. SOURCE_DATE_EPOCH pins the build timestamp for reproducible builds.

For broker inventory, consumers pass these fields and one process-start timestamp to RegisterProvenance::from_parts from cosmix-lib-bus, then connect with NodedClient::connect_with_provenance or the supervised equivalent.

See also

  • wire format — RegisterProvenance, ServiceInfo, and NodeInfo
  • client — provenance-aware registration and reconnect
  • overview — the crate family