From 4609173f5d638692944d5e66731fec856c9efdfc Mon Sep 17 00:00:00 2001
From: Phil Porada <pporada@letsencrypt.org>
Date: Fri, 22 May 2026 12:37:37 -0700
Subject: [PATCH] Add a build metric

---
 cmd/sunlight/sunlight.go | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/cmd/sunlight/sunlight.go b/cmd/sunlight/sunlight.go
index 4c903c9..185cb55 100644
--- a/cmd/sunlight/sunlight.go
+++ b/cmd/sunlight/sunlight.go
@@ -392,6 +392,25 @@ func main() {
 	}))
 	sunlightMetrics := prometheus.WrapRegistererWithPrefix("sunlight_", metrics)
 
+	buildInfo, _ := debug.ReadBuildInfo()
+	buildVersion := buildInfo.Main.Version
+	buildCommit := ""
+	for _, s := range buildInfo.Settings {
+		if s.Key == "vcs.revision" {
+			buildCommit = s.Value
+			break
+		}
+	}
+	buildInfoGauge := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "sunlight_build_info",
+			Help: "Build information about the running sunlight binary.",
+		},
+		[]string{"version", "commit"},
+	)
+	buildInfoGauge.WithLabelValues(buildVersion, buildCommit).Set(1)
+	metrics.MustRegister(buildInfoGauge)
+
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer stop()