Initial metrics endpoint added in Prometheus style

logging/logging.go

@@ -1,6 +1,7 @@
 package logging
 
 import (
+	"fs/metrics"
 	"log/slog"
 	"net/http"
 	"os"
@@ -9,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
 )
 
@@ -86,6 +88,8 @@ func HTTPMiddleware(logger *slog.Logger, cfg Config) func(http.Handler) http.Han
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			start := time.Now()
 			ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+			metrics.Default.IncHTTPInFlight()
+			defer metrics.Default.DecHTTPInFlight()
 			requestID := middleware.GetReqID(r.Context())
 			if requestID != "" {
 				ww.Header().Set("x-amz-request-id", requestID)
@@ -93,15 +97,18 @@ func HTTPMiddleware(logger *slog.Logger, cfg Config) func(http.Handler) http.Han
 
 			next.ServeHTTP(ww, r)
 
-			if !cfg.Audit && !cfg.DebugMode {
-				return
-			}
-
 			elapsed := time.Since(start)
 			status := ww.Status()
 			if status == 0 {
 				status = http.StatusOK
 			}
+			route := metricRouteLabel(r)
+			metrics.Default.ObserveHTTPRequest(r.Method, route, status, elapsed, ww.BytesWritten())
+
+			if !cfg.Audit && !cfg.DebugMode {
+				return
+			}
+
 			attrs := []any{
 				"method", r.Method,
 				"path", r.URL.Path,
@@ -131,6 +138,35 @@ func HTTPMiddleware(logger *slog.Logger, cfg Config) func(http.Handler) http.Han
 	}
 }
 
+func metricRouteLabel(r *http.Request) string {
+	if r == nil || r.URL == nil {
+		return "/unknown"
+	}
+
+	if routeCtx := chi.RouteContext(r.Context()); routeCtx != nil {
+		if pattern := strings.TrimSpace(routeCtx.RoutePattern()); pattern != "" {
+			return pattern
+		}
+	}
+
+	path := strings.TrimSpace(r.URL.Path)
+	if path == "" || path == "/" {
+		return "/"
+	}
+	if path == "/healthz" || path == "/metrics" {
+		return path
+	}
+
+	trimmed := strings.Trim(path, "/")
+	if trimmed == "" {
+		return "/"
+	}
+	if !strings.Contains(trimmed, "/") {
+		return "/{bucket}"
+	}
+	return "/{bucket}/*"
+}
+
 func envBool(key string, defaultValue bool) bool {
 	raw := os.Getenv(key)
 	if raw == "" {

logging/logging_metrics_test.go

@@ -0,0 +1,30 @@
+package logging
+
+import (
+	"net/http/httptest"
+	"testing"
+)
+
+func TestMetricRouteLabelFallbacks(t *testing.T) {
+	testCases := []struct {
+		name string
+		path string
+		want string
+	}{
+		{name: "root", path: "/", want: "/"},
+		{name: "health", path: "/healthz", want: "/healthz"},
+		{name: "metrics", path: "/metrics", want: "/metrics"},
+		{name: "bucket", path: "/some-bucket", want: "/{bucket}"},
+		{name: "object", path: "/some-bucket/private/path/file.jpg", want: "/{bucket}/*"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			req := httptest.NewRequest("GET", tc.path, nil)
+			got := metricRouteLabel(req)
+			if got != tc.want {
+				t.Fatalf("metricRouteLabel(%q) = %q, want %q", tc.path, got, tc.want)
+			}
+		})
+	}
+}