.. _well_known_dynamic_metadata: Well Known Dynamic Metadata =========================== Filters can emit dynamic metadata via the *setDynamicMetadata* routine in the :repo:`StreamInfo ` interface on a :repo:`Connection `. This metadata emitted by a filter can be consumed by other filters and useful features can be built by stacking such filters. For example, a logging filter can consume dynamic metadata from an RBAC filter to log details about runtime shadow rule behavior. Another example is where an RBAC filter permits/restricts MySQL/MongoDB operations by looking at the operational metadata emitted by the MongoDB filter. The following Envoy filters emit dynamic metadata that other filters can leverage. * :ref:`Mongo Proxy Filter ` * :ref:`MySQL Proxy Filter ` * :ref:`Role Based Access Control (RBAC) Filter ` * :ref:`Role Based Access Control (RBAC) Network Filter ` * :ref:`ZooKeeper Proxy Filter ` The following Envoy filters can be configured to consume dynamic metadata emitted by other filters. * :ref:`RateLimit Filter limit override `