Fix accumulating log attributes

`logger` is a closure here, so overwriting it on every request isn't a good idea.

log/log.go

@@ -21,7 +21,7 @@ func Request(next http.Handler, logger log.Logger) http.Handler {
 			remote = r.RemoteAddr
 		}
 
-		logger = log.With(logger,
+		l := log.With(logger,
 			"method", r.Method,
 			"url", r.URL,
 			"remote", remote,
@@ -31,13 +31,13 @@ func Request(next http.Handler, logger log.Logger) http.Handler {
 		defer func() {
 			d := time.Since(start)
 
-			level.Info(logger).
+			level.Info(l).
 				Log("duration", d,
 					"msg", "request handled")
 		}()
 
 		key := contextKey("logger")
-		ctx := context.WithValue(r.Context(), key, logger)
+		ctx := context.WithValue(r.Context(), key, l)
 
 		next.ServeHTTP(w, r.WithContext(ctx))
 	})