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Remove Headers

Overview​

The Remove Headers Traffic Policy action enables you to remove headers from an HTTP request before it is sent upstream or from an HTTP response before it is sent back to the client.

Configuration Reference​

The Traffic Policy configuration reference for this action.

Supported Phases​

on_http_request, on_http_response

Type​

remove-headers

Configuration Fields​

  • headersarray of stringsRequired

    List of header keys to remove from the request or response.

    Minimum 1, Maximum 10.

Behavior​

On on_http_request​

When executed during the on_http_request phase, this action will remove the specified headers from incoming HTTP requests before reaching the upstream server.

On on_http_response​

When executed during the on_http_response, the configured headers are removed from HTTP responses returned from the upstream server before reaching the client.

Removal Only​

This action will only remove headers from the request or response.

  • If you want to add a header use the add-headers action.
  • If you want to replace a header, first use this action then use the add-headers action.

Ordering​

Since actions are run in the order they are specified, to modify headers that have been added by other actions you must place this action after them in your traffic policy document.

Special Cases​

  • You may not add or remove the user-agent header.

Examples​

Removing headers from all requests​

We have been getting a lot of requests with x-client-version and x-trace-id and it is starting to overwhelm our logging system. We want to remove these headers from all requests. The following example demonstrates how to remove these headers using the remove-headers action.

Example Traffic Policy Document​

---
on_http_request:
  - actions:
      - type: remove-headers
        config:
          headers:
            - x-client-version
            - x-trace-id

For this example, we are assuming that ngrok is pointing at the upstream service https://httpbin.org.

Example Request​

$ curl -H "x-client-version: 3.1" -H "x-trace-id: abc123" https://httpbin.ngrok.app/get
< HTTP/2 200

{
...
  "headers": {
    "Date": "2024-06-24T15:30:00Z",
  }
...
}

In this example even though we sent the x-client-version and x-trace-id headers, they were not present on the request that was sent upstream.

Action Result Variables​

The following variables are made available for use in subsequent expressions and CEL interpolations after the action has run. Variable values will only apply to the last action execution, results are not concatenated.

  • actions.ngrok.remove_headers.headers_removedarray of strings

    A list of headers that were successfully removed by the action.