feat: use random counter

deploy/k8s/namespace.yaml

@@ -1,4 +0,0 @@
-apiVersion: v1
-kind: Namespace
-metadata:
-  name: metrics-counter

main.go

@@ -1,11 +1,12 @@
 package main
 
 import (
+	"context"
 	"log"
+	"math/rand"
 	"net/http"
 	"os"
 	"os/signal"
-	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -13,32 +14,26 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-var (
-	counter = prometheus.NewCounterVec(
+var counter = prometheus.NewCounterVec(
 	prometheus.CounterOpts{
-			Name: "custom_counter_total",
-			Help: "A counter that increments every 30 seconds",
+		Name: "random_counter_total",
+		Help: "A counter that increments randomly from 1 to 30 seconds",
 	},
 	[]string{},
-	)
-	counterValue uint64
 )
 
 func main() {
 	// Register Prometheus metrics
 	prometheus.MustRegister(counter)
 
-	// Start background counter incrementer
-	go incrementCounterEvery30s()
-
 	// Set up HTTP server
 	http.Handle("/metrics", promhttp.Handler())
 	server := &http.Server{Addr: ":8080"}
 
-	// Handle graceful shutdown
-	stop := make(chan os.Signal, 1)
-	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
 
+	go startCounting(ctx)
 	go func() {
 		log.Println("Starting server on :8080")
 		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
@@ -46,17 +41,23 @@ func main() {
 		}
 	}()
 
-	<-stop
-	log.Println("\nShutting down server...")
+	<-ctx.Done()
+	log.Println("Shutdown the server")
+	// Give one more second for gracefully shutdown
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	server.Shutdown(ctx)
 }
 
-func incrementCounterEvery30s() {
-	ticker := time.NewTicker(30 * time.Second)
-	defer ticker.Stop()
-
-	for range ticker.C {
-		newVal := atomic.AddUint64(&counterValue, 1)
+func startCounting(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
 			counter.WithLabelValues().Add(1)
-		log.Printf("Counter incremented to %d", newVal)
+			sleepDuration := time.Duration(rand.Intn(29) + 1)
+			time.Sleep(sleepDuration * time.Second)
+		}
 	}
 }