add basic metrics for stress testing

proxy/internal/metrics/metrics.go

@@ -0,0 +1,56 @@
+package metrics
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+type Metrics struct {
+	requestsTotal   prometheus.Counter
+	requestDuration prometheus.Histogram
+	activeRequests  prometheus.Counter
+	backendDuration prometheus.Histogram
+}
+
+func New(reg prometheus.Registerer) *Metrics {
+	return &Metrics{
+		requestsTotal: promauto.With(reg).NewCounter(prometheus.CounterOpts{
+			Name: "netbird_proxy_requests_total",
+			Help: "Total number of requests made to the netbird proxy",
+		}),
+		requestDuration: promauto.With(reg).NewHistogram(prometheus.HistogramOpts{
+			Name:    "netbird_proxy_request_duration_seconds",
+			Help:    "Duration of requests made to the netbird proxy",
+			Buckets: []float64{0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10},
+		}),
+		activeRequests: promauto.With(reg).NewCounter(prometheus.CounterOpts{
+			Name: "netbird_proxy_active_requests_total",
+			Help: "Current in-flight requests handled by the netbird proxy",
+		}),
+		backendDuration: promauto.With(reg).NewHistogram(prometheus.HistogramOpts{
+			Name:    "netbird_proxy_backend_duration_seconds",
+			Help:    "Duration of peer round trip time from the netbird proxy",
+			Buckets: []float64{0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10},
+		}),
+	}
+}
+
+func (m *Metrics) Middleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		m.requestsTotal.Inc()
+		m.activeRequests.Inc()
+
+		start := time.Now()
+		next.ServeHTTP(w, r)
+
+		m.activeRequests.Desc()
+		m.requestDuration.Observe(time.Since(start).Seconds())
+	})
+}
+
+func (m *Metrics) CompleteRoundTrip(t time.Duration) {
+	m.backendDuration.Observe(t.Seconds())
+}