Adding OpenTelemetry Metrics and Tracing

internal/telemetry/telemetry_smoke_test.go

@@ -0,0 +1,65 @@
+package telemetry
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+)
+
+// Smoke test that /metrics contains at least one newt_* metric when Prom exporter is enabled.
+func TestMetricsSmoke(t *testing.T) {
+	ctx := context.Background()
+	resetMetricsForTest()
+	t.Setenv("NEWT_METRICS_INCLUDE_SITE_LABELS", "true")
+	cfg := Config{
+		ServiceName:          "newt",
+		PromEnabled:          true,
+		OTLPEnabled:          false,
+		AdminAddr:            "127.0.0.1:0",
+		BuildVersion:         "test",
+		BuildCommit:          "deadbeef",
+		MetricExportInterval: 5 * time.Second,
+	}
+	tel, err := Init(ctx, cfg)
+	if err != nil {
+		t.Fatalf("telemetry init error: %v", err)
+	}
+	defer func() { _ = tel.Shutdown(context.Background()) }()
+
+	// Serve the Prom handler on a test server
+	if tel.PrometheusHandler == nil {
+		t.Fatalf("Prometheus handler nil; PromEnabled should enable it")
+	}
+	ts := httptest.NewServer(tel.PrometheusHandler)
+	defer ts.Close()
+
+	// Record a simple metric and then fetch /metrics
+	IncConnAttempt(ctx, "websocket", "success")
+	if tel.MeterProvider != nil {
+		_ = tel.MeterProvider.ForceFlush(ctx)
+	}
+	// Give the exporter a tick to collect
+	time.Sleep(100 * time.Millisecond)
+
+	var body string
+	for i := 0; i < 5; i++ {
+		resp, err := http.Get(ts.URL)
+		if err != nil {
+			t.Fatalf("GET /metrics failed: %v", err)
+		}
+		b, _ := io.ReadAll(resp.Body)
+		_ = resp.Body.Close()
+		body = string(b)
+		if strings.Contains(body, "newt_connection_attempts_total") {
+			break
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	if !strings.Contains(body, "newt_connection_attempts_total") {
+		t.Fatalf("expected newt_connection_attempts_total in metrics, got:\n%s", body)
+	}
+}