feat: added Argo version info in /metrics endpoint

controller/metrics/metrics.go

@@ -75,6 +75,7 @@ func NewMetricsServer(cfg ServerConfig, isPrimary bool) *MetricsServer {
 	reg.MustRegister(MetricExperimentReconcileError)
 	reg.MustRegister(MetricAnalysisRunReconcile)
 	reg.MustRegister(MetricAnalysisRunReconcileError)
+	reg.MustRegister(MetricVersionGauge)
 
 	mux.Handle(MetricsPath, promhttp.HandlerFor(prometheus.Gatherers{
 		// contains app controller specific metrics

controller/metrics/metrics_test.go

@@ -89,6 +89,13 @@ rollout_reconcile_error{name="name",namespace="ns"} 1`
 	testHttpResponse(t, metricsServ.Handler, expectedResponse)
 }
 
+func TestVersionInfo(t *testing.T) {
+	expectedResponse := `# HELP argo_rollouts_controller_info Running Argo-rollouts version
+# TYPE argo_rollouts_controller_info gauge`
+	metricsServ := NewMetricsServer(newFakeServerConfig(), true)
+	testHttpResponse(t, metricsServ.Handler, expectedResponse)
+}
+
 func TestSecondaryMetricsServer(t *testing.T) {
 	expectedResponse := ``
 

controller/metrics/prommetrics.go

@@ -1,6 +1,9 @@
 package metrics
 
-import "github.com/prometheus/client_golang/prometheus"
+import (
+	"github.com/argoproj/argo-rollouts/utils/version"
+	"github.com/prometheus/client_golang/prometheus"
+)
 
 // Follow Prometheus naming practices
 // https://prometheus.io/docs/practices/naming/
@@ -184,3 +187,17 @@ var (
 		[]string{"kind", "namespace", "name", "verb", "status_code"},
 	)
 )
+
+// MetricVersionGauge version info
+var (
+	MetricVersionGauge = prometheus.NewGaugeFunc(
+		prometheus.GaugeOpts{
+			Name:        "argo_rollouts_controller_info",
+			Help:        "Running Argo-rollouts version",
+			ConstLabels: prometheus.Labels{"version": version.GetVersion().Version},
+		},
+		func() float64 {
+			return float64(1)
+		},
+	)
+)