Well Known Dynamic Metadata

Filters can emit dynamic metadata via the setDynamicMetadata routine in the StreamInfo interface on a 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.

• Mongo Proxy Filter

• MySQL Proxy Filter

• Role Based Access Control (RBAC) Filter

• Role Based Access Control (RBAC) Network Filter

• ZooKeeper Proxy Filter

The following Envoy filters can be configured to consume dynamic metadata emitted by other filters.

• RateLimit Filter limit override