Use a URL parameter in a transform rule

[kevin87]

I am trying to set a cookie using a transform rule like the example given here:

Transform Rules - Response Header New Action "Add"

Hi Everyone, I am excited to announce that Cloudflare Transform Rules now allow you to “Add” a HTTP Response Header that does not remove/overwrite existing matching Response Header values. A common use case for this is to set-cookie headers. Within Transform Rules, customers using the ‘Set’ operations and the Header Name ‘set-cookie’ would remove any cookies being applied from the Origin or Cloudflare features. Returning only those set within the Transform Rules rule to the end user. Today, y…

However, I would like the cookie value to be based on a value found in the URI.

For example, if my URI contains ?clickid=12345

Set the cookie: “_clickid=12345;max-age=604800;Path=/”

Is there any way to reference a URI parameter value in a transform rule?

[cbrandt]

You can use http.request.uri.query to add the query string to your header. And the concat() function to concatenate the full content of your header.

Functions reference · Cloudflare Ruleset Engine docs