Configure Transform Rules

This page provides examples of creating Transform Rules in a zone using Terraform. The examples cover the following scenarios:

• Create a Rewrite URL Rule
• Create an HTTP Request Header Modification Rule

For more information on Transform Rules, refer to Transform Rules.

​​ Create a Rewrite URL Rule

The following example creates a Rewrite URL Rule that rewrites requests for example.com/old-folder to example.com/new-folder:

resource "cloudflare_ruleset" "transform_url_rewrite" {
  zone_id     = "<ZONE_ID>"
  name        = "Transform Rule performing a static URL rewrite"
  description = ""
  kind        = "zone"
  phase       = "http_request_transform"
  rules {
    action = "rewrite"
    action_parameters {
      uri {
        path {
          value = "/new-folder"
        }
      }
    }
    expression = "(http.host eq \"example.com\" and http.request.uri.path eq \"/old-folder\")"
    description = "Example Rewrite URL Rule"
    enabled = true
  }
}

For more information on rewriting URLs, refer to Rewrite URL Rules.

​​ Create an HTTP Request Header Modification Rule

The following configuration example performs the following adjustments to HTTP request headers:

• Adds a my-header-1 header to the request with a static value.
• Adds a my-header-2 header to the request with a dynamic value defined by an expression.
• Deletes the existing-header header from the request, if it exists.

resource "cloudflare_ruleset" "transform_modify_request_headers" {
  zone_id     = "<ZONE_ID>"
  name        = "Transform Rule performing HTTP request header modifications"
  description = ""
  kind        = "zone"
  phase       = "http_request_late_transform"
  rules {
    action = "rewrite"
    action_parameters {
      headers {
        name      = "my-header-1"
        operation = "set"
        value     = "Fixed value"
      }
      headers {
        name       = "my-header-2"
        operation  = "set"
        expression = "cf.zone.name"
      }
      headers {
        name      = "existing-header"
        operation = "remove"
      }
    }
    expression = "true"
    description = "Example HTTP Request Header Modification Rule"
    enabled = true
  }
}

For more information on modifying request headers, refer to HTTP Request Header Modification Rules.

​​ Create an HTTP Response Header Modification Rule

The following configuration example performs the following adjustments to HTTP response headers:

• Adds a my-header-1 header to the response with a static value.
• Adds a my-header-2 header to the response with a dynamic value defined by an expression.
• Deletes the existing-header header from the response, if it exists.

resource "cloudflare_ruleset" "transform_modify_response_headers" {
  zone_id     = "<ZONE_ID>"
  name        = "Transform Rule performing HTTP response header modifications"
  description = ""
  kind        = "zone"
  phase       = "http_response_headers_transform"
  rules {
    action = "rewrite"
    action_parameters {
      headers {
        name      = "my-header-1"
        operation = "set"
        value     = "Fixed value"
      }
      headers {
        name       = "my-header-2"
        operation  = "set"
        expression = "cf.zone.name"
      }
      headers {
        name      = "existing-header"
        operation = "remove"
      }
    }
    expression = "true"
    description = "Example HTTP Response Header Modification Rule"
    enabled = true
  }
}

For more information on modifying response headers, refer to HTTP Response Header Modification Rules.