fix memory usage redis

tests/test_config.py

@@ -37,6 +37,16 @@ class ConfigTests(unittest.TestCase):
         self.assertEqual(cfg.metrics_basic_auth_username, "prometheus")
         self.assertEqual(cfg.metrics_basic_auth_password, "secret")
 
+    def test_redis_buffer_defaults_are_bounded_and_archive_is_fast(self):
+        with patch.dict(os.environ, {}, clear=True):
+            cfg = Config.from_env()
+        self.assertEqual(cfg.redis_maxmemory_mb, 128)
+        self.assertEqual(cfg.redis_snapshot_seconds, 0)
+        self.assertFalse(cfg.redis_aof)
+        self.assertEqual(cfg.traffic_archive_interval_seconds, 5)
+        self.assertEqual(cfg.traffic_archive_lag_seconds, 10)
+        self.assertEqual(cfg.traffic_archive_batch_size, 1000)
+
 
 if __name__ == "__main__":
     unittest.main()