Scope the rate limit counter key by source AND by middleware

pkg/middlewares/ratelimiter/rate_limiter.go

@@ -146,7 +146,12 @@ func (rl *rateLimiter) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		logger.Info().Msgf("ignoring token bucket amount > 1: %d", amount)
 	}
 
-	delay, err := rl.limiter.Allow(ctx, source)
+	// Each rate limiter has its own source space,
+	// ensuring independence between rate limiters,
+	// i.e., rate limit rules are only applied based on traffic
+	// where the rate limiter is active.
+	rlSource := fmt.Sprintf("%s:%s", rl.name, source)
+	delay, err := rl.limiter.Allow(ctx, rlSource)
 	if err != nil {
 		rl.logger.Error().Err(err).Msg("Could not insert/update bucket")
 		observability.SetStatusErrorf(ctx, "Could not insert/update bucket")