The Modify Headers policy can set or remove headers on requests.
Headers prefixed with
kong/are reserved for Event Gateway internal use. The Modify Headers policy doesn’t prevent you from reading, writing, or modifying them, but doing so isn’t recommended and can interfere with Event Gateway behavior. For the full list of reserved headers, see the Kong Event Gateway headers reference.
Common use cases for the Modify Headers policy:
|
Use case |
Description |
|---|---|
| Example: Remove and replace a header | Remove a specific header and replace it with a custom header of your choice. |
| Example: Add a header based on a condition | If a record fits a specific condition, add a custom header of your choice. |
| Tutorial: Filter Kafka records by classification headers | Use a Schema Validation policy to parse JSON records, and use a nested Modify Headers policy to add a header to specific records. |
This policy runs in the produce or consume phase.
For produced messages:
For consumed messages:
sequenceDiagram autonumber participant client as Client participant egw as Event Gateway participant broker as Event broker client->>egw: produce message egw->>egw: remove or add headers egw->>broker: send message broker->>egw: consume message egw->>egw: remove or add headers egw->>client: pass message with new headers
This policy can be applied directly to the virtual cluster, or be nested within a Schema Validation policy. See the policy nesting example to learn how to apply a Modify Headers policy to a parent.
Nested policies are sorted into an index. You can re-order nested policies within the parent policy by adjusting this index. See the reference for nested policies for more detail.