From b3356a2edabfeffd11d420df1dac6c5c745279ed Mon Sep 17 00:00:00 2001
From: Nicolas Lamirault <nicolas.lamirault@gmail.com>
Date: Fri, 6 Dec 2024 17:12:10 +0100
Subject: [PATCH] feat: New Prometheus metric: build_info (#3591)

* new Prometheus metrics build_info

Signed-off-by: Nicolas Lamirault <nicolas.lamirault@gmail.com>

* fix: gofmt

Signed-off-by: Nicolas Lamirault <nicolas.lamirault@gmail.com>

---------

Signed-off-by: Nicolas Lamirault <nicolas.lamirault@gmail.com>
---
 controller/metrics/metrics.go | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/controller/metrics/metrics.go b/controller/metrics/metrics.go
index 9691b73a40..d06fbbfe37 100644
--- a/controller/metrics/metrics.go
+++ b/controller/metrics/metrics.go
@@ -2,6 +2,7 @@ package metrics
 
 import (
 	"net/http"
+	"runtime"
 	"time"
 
 	"github.com/argoproj/argo-rollouts/utils/defaults"
@@ -16,6 +17,7 @@ import (
 	"github.com/argoproj/argo-rollouts/pkg/apis/rollouts/v1alpha1"
 	rolloutlister "github.com/argoproj/argo-rollouts/pkg/client/listers/rollouts/v1alpha1"
 	"github.com/argoproj/argo-rollouts/utils/log"
+	"github.com/argoproj/argo-rollouts/utils/version"
 )
 
 type MetricsServer struct {
@@ -39,6 +41,16 @@ const (
 	MetricsPath = "/metrics"
 )
 
+var (
+	buildInfo = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "build_info",
+			Help: "A metric with a constant '1' value labeled by version from which Argo-Rollouts was built.",
+		},
+		[]string{"version", "goversion", "goarch", "commit"},
+	)
+)
+
 type ServerConfig struct {
 	Addr                          string
 	RolloutLister                 rolloutlister.RolloutLister
@@ -74,6 +86,9 @@ func NewMetricsServer(cfg ServerConfig) *MetricsServer {
 	reg.MustRegister(MetricNotificationFailedTotal)
 	reg.MustRegister(MetricNotificationSend)
 	reg.MustRegister(MetricVersionGauge)
+	reg.MustRegister(buildInfo)
+
+	recordBuildInfo()
 
 	mux.Handle(MetricsPath, promhttp.HandlerFor(prometheus.Gatherers{
 		// contains app controller specific metrics
@@ -174,6 +189,12 @@ func (m *MetricsServer) Remove(namespace string, name string, kind string) {
 
 }
 
+// recordBuildInfo publishes information about Argo-Rollouts version and runtime info through an info metric (gauge).
+func recordBuildInfo() {
+	vers := version.GetVersion()
+	buildInfo.WithLabelValues(vers.Version, runtime.Version(), runtime.GOARCH, vers.GitCommit).Set(1)
+}
+
 func boolFloat64(b bool) float64 {
 	if b {
 		return 1