feat: Track the last time we updated the metrics

main.go

@@ -28,7 +28,7 @@ type CertificateMetrics struct {
 	IsValid  prometheus.Gauge
 }
 
-func NewCertificateMetrics(domain string, port int, alpn []string) CertificateMetrics {
+func NewCertificateMetrics(domain string, port int, alpn []string, name string) CertificateMetrics {
 	metrics := CertificateMetrics{
 		Domain: domain,
 		Port:   port,
@@ -36,13 +36,13 @@ func NewCertificateMetrics(domain string, port int, alpn []string) CertificateMe
 		ExpiryIn: prometheus.NewGauge(
 			prometheus.GaugeOpts{
 				Name:        "cert_status_expiry_in",
-				ConstLabels: prometheus.Labels{"domain": domain},
+				ConstLabels: prometheus.Labels{"name": name},
 			},
 		),
 		IsValid: prometheus.NewGauge(
 			prometheus.GaugeOpts{
 				Name:        "cert_status_is_valid",
-				ConstLabels: prometheus.Labels{"domain": domain},
+				ConstLabels: prometheus.Labels{"name": name},
 			},
 		),
 	}
@@ -88,8 +88,9 @@ func (c *CertificateMetrics) checkTls() {
 	}
 }
 
-func updateMetrics(metrics *[]CertificateMetrics) {
+func updateMetrics(metrics *[]CertificateMetrics, lastUpdated prometheus.Gauge) {
 	log.Debugf("Updating metrics for %d domains...", len(*metrics))
+	lastUpdated.SetToCurrentTime()
 	for _, metric := range *metrics {
 		metric.checkTls()
 	}
@@ -108,15 +109,29 @@ func run(ctx *cli.Context) error {
 
 	// Setup metrics
 	registry := prometheus.NewRegistry()
+	lastUpdatedMetric := prometheus.NewGauge(
+		prometheus.GaugeOpts{
+			Name: "certs_status_last_updated",
+		},
+	)
+	registry.MustRegister(lastUpdatedMetric)
+
 	metrics := make([]CertificateMetrics, 0)
 	for _, d := range domains {
 		log.Debugf("Parsing '%s'...", d)
 		parts := strings.Split(d, ":")
-		if len(parts) != 3 {
+		if len(parts) < 3 {
 			log.Errorf("Invalid domain format for '%s'", d)
 			return errors.New("Invalid domain format: Expects <domain>:<port>:<alpn>")
 		}
 
+		name := ""
+		if len(parts) == 4 {
+			name = parts[3]
+		} else {
+			name = parts[0]
+		}
+
 		port, err := strconv.Atoi(parts[1])
 		if err != nil {
 			log.Errorf("Failed to parse port of '%s'", d)
@@ -126,11 +141,12 @@ func run(ctx *cli.Context) error {
 		// Create the metric, and register it
 		// TODO: Make this prettier
 		alpn := strings.Split(parts[2], ";")
-		log.Debugf("Using ALPNs: %v", alpn)
+		log.Debugf("Registering: domain='%s' port='%d' alpn=%v name='%s'", parts[0], port, alpn, name)
 		metric := NewCertificateMetrics(
 			parts[0],
 			port,
 			alpn,
+			name,
 		)
 		metric.register(registry)
 		metrics = append(metrics, metric)
@@ -147,7 +163,7 @@ func run(ctx *cli.Context) error {
 		gocron.DurationJob(24*time.Hour),
 		gocron.NewTask(
 			func() {
-				updateMetrics(&metrics)
+				updateMetrics(&metrics, lastUpdatedMetric)
 			},
 		),
 	)
@@ -158,7 +174,7 @@ func run(ctx *cli.Context) error {
 
 	// Perform an initial run to populate the metrics
 	log.Info("Performing initial requests...")
-	updateMetrics(&metrics)
+	updateMetrics(&metrics, lastUpdatedMetric)
 	log.Debug("Done")
 
 	http.Handle(