feat(metrics): wire instrumentation through queue, handlers, middleware

internal/api/middleware.go

@@ -7,10 +7,12 @@ import (
 	"fmt"
 	"log/slog"
 	"net/http"
+	"strconv"
 	"strings"
 	"time"
 
 	"github.com/shcizo/package-updater/internal/logging"
+	"github.com/shcizo/package-updater/internal/metrics"
 )
 
 // Auth returns middleware that requires a matching bearer token.
@@ -66,8 +68,9 @@ func RequestID(next http.Handler) http.Handler {
 	})
 }
 
-// RequestLogger emits a structured access-log line per request.
-func RequestLogger(base *slog.Logger) func(http.Handler) http.Handler {
+// RequestLogger emits a structured access-log line per request. m may be nil,
+// in which case metrics recording is silently skipped.
+func RequestLogger(base *slog.Logger, m *metrics.Metrics) func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			start := time.Now()
@@ -81,6 +84,9 @@ func RequestLogger(base *slog.Logger) func(http.Handler) http.Handler {
 				"duration_ms", time.Since(start).Milliseconds(),
 				"client_ip", clientIP(r),
 			)
+			if m != nil {
+				m.HTTPRequests.WithLabelValues(r.URL.Path, strconv.Itoa(sw.status)).Inc()
+			}
 		})
 	}
 }