feat: add start time metric (#13)

pkg/app.go

@@ -38,6 +38,7 @@ func NewApp(configPath string) *App {
 	queriers := []types.Querier{
 		queriersPkg.NewPriceQuerier(appConfig, coingecko),
 		queriersPkg.NewBalanceQuerier(appConfig, log),
+		queriersPkg.NewUptimeQuerier(),
 	}
 
 	return &App{

pkg/queriers/uptime.go

@@ -0,0 +1,31 @@
+package queriers
+
+import (
+	"main/pkg/types"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type UptimeQuerier struct {
+	StartTime time.Time
+}
+
+func NewUptimeQuerier() *UptimeQuerier {
+	return &UptimeQuerier{
+		StartTime: time.Now(),
+	}
+}
+
+func (u *UptimeQuerier) GetMetrics() ([]prometheus.Collector, []types.QueryInfo) {
+	uptimeMetricsGauge := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "cosmos_wallets_exporter_start_time",
+			Help: "Unix timestamp on when the app was started. Useful for annotations.",
+		},
+		[]string{},
+	)
+
+	uptimeMetricsGauge.With(prometheus.Labels{}).Set(float64(u.StartTime.Unix()))
+	return []prometheus.Collector{uptimeMetricsGauge}, []types.QueryInfo{}
+}