init

main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"context"
+	"log/slog"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var (
+	times = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Name:    "app_times_seconds",
+		Buckets: []float64{0.01, 0.013, 0.015, 0.02, 0.03, 0.04, 0.05, 0.06, 1, 2, 3, 4, 5, 6, 7},
+	}, []string{"status"})
+	timesSummary = promauto.NewSummaryVec(prometheus.SummaryOpts{
+		Name:       "app_times_summary_seconds",
+		Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+	}, []string{"status"})
+	timesNative = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Name:                        "app_times_native_seconds",
+		NativeHistogramBucketFactor: 1.1,
+	}, []string{"status"})
+)
+
+func main() {
+	slog.Info("application started")
+	if err := start(context.Background()); err != nil {
+		slog.Error("unable to start application", "error", err)
+		os.Exit(1)
+	}
+
+	slog.Info("application stopped")
+}
+
+func start(_ context.Context) error {
+	port := os.Getenv("APP_PORT")
+	go func() {
+		var max time.Duration
+		for {
+			t := time.Now()
+			time.Sleep(10 * time.Millisecond)
+			duration := time.Since(t)
+			times.WithLabelValues("10ms").Observe(duration.Seconds())
+			timesNative.WithLabelValues("10ms").Observe(duration.Seconds())
+			timesSummary.WithLabelValues("10ms").Observe(duration.Seconds())
+			if duration > max {
+				max = duration
+			}
+			slog.Info("duration", "duration", duration, "max", max)
+		}
+	}()
+	go func() {
+		var max time.Duration
+		for {
+			t := time.Now()
+			time.Sleep(100 * time.Millisecond)
+			duration := time.Since(t)
+			times.WithLabelValues("100ms").Observe(duration.Seconds())
+			timesNative.WithLabelValues("100ms").Observe(duration.Seconds())
+			timesSummary.WithLabelValues("100ms").Observe(duration.Seconds())
+			if duration > max {
+				max = duration
+			}
+			// slog.Info("duration", "duration", duration, "max", max)
+		}
+	}()
+
+	http.Handle("/metrics", promhttp.Handler())
+	return http.ListenAndServe(":"+port, nil)
+}