Create an HTTP response header modification rule via API
Use the Rulesets API to create HTTP response header modification rules via API. Refer to Response header modification examples for common use cases.
Basic rule settings
When creating an HTTP response header modification rule via API, make sure you:
- Set the rule action to
rewrite. - Define the header modification parameters in the
action_parametersfield according to the operation to perform (set, add, or remove header). - Deploy the rule to the
http_response_headers_transformphase at the zone level.
Procedure
Follow this workflow to create an HTTP response header modification rule for a given zone via API:
Use the List zone rulesets operation to check if there is already a ruleset for the
http_response_headers_transformphase at the zone level.If the phase ruleset does not exist, create it using the Create a zone ruleset operation. In the new ruleset properties, set the following values:
- kind:
zone - phase:
http_response_headers_transform
- kind:
Use the Update a zone ruleset operation to add an HTTP response header modification rule to the list of ruleset rules. Alternatively, include the rule in the Create a zone ruleset request mentioned in the previous step.
Make sure your API token has the required permissions to perform the API operations.
Example requests
Example: Set an HTTP response header to a static value
The following example configures the rules of an existing phase ruleset ({ruleset_id}) to a single HTTP response header modification rule — setting an HTTP response header to a static value — using the Update a zone ruleset operation:
Requestcurl --request PUT \https://api.cloudflare.com/client/v4/zones/{zone_id}/rulesets/{ruleset_id} \
--header "Authorization: Bearer <API_TOKEN>" \
--header "Content-Type: application/json" \
--data '{ "rules": [ { "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "action": "rewrite", "action_parameters": { "headers": { "X-Source": { "operation": "set", "value": "Cloudflare" } } } } ]}'
The response contains the complete definition of the ruleset you updated.
Response{ "result": { "id": "<RULESET_ID>", "name": "Zone-level Response Headers Transform Ruleset", "description": "Zone-level ruleset that will execute Response Header Modification Rules.", "kind": "zone", "version": "2", "rules": [ { "id": "<RULE_ID>", "version": "1", "action": "rewrite", "action_parameters": { "headers": { "X-Source": { "operation": "set", "value": "Cloudflare" } } }, "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "last_updated": "2021-04-14T14:42:04.219025Z", "ref": "<RULE_REF>" } ], "last_updated": "2021-04-14T14:42:04.219025Z", "phase": "http_response_headers_transform" }, "success": true, "errors": [], "messages": []
}
Example: Set an HTTP response header to a dynamic value
The following example configures the rules of an existing phase ruleset ({ruleset_id}) to a single HTTP response header modification rule — setting an HTTP response header to a dynamic value — using the Update a zone ruleset operation:
Requestcurl --request PUT \https://api.cloudflare.com/client/v4/zones/{zone_id}/rulesets/{ruleset_id} \
--header "Authorization: Bearer <API_TOKEN>" \
--header "Content-Type: application/json" \
--data '{ "rules": [ { "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "action": "rewrite", "action_parameters": { "headers": { "X-Bot-Score": { "operation": "set", "expression": "to_string(cf.bot_management.score)" } } } } ]}'
The response contains the complete definition of the ruleset you updated.
Response{ "result": { "id": "<RULESET_ID>", "name": "Zone-level Response Headers Transform Ruleset", "description": "Zone-level ruleset that will execute Response Header Modification Rules.", "kind": "zone", "version": "2", "rules": [ { "id": "<RULE_ID>", "version": "1", "action": "rewrite", "action_parameters": { "headers": { "X-Bot-Score": { "operation": "set", "expression": "to_string(cf.bot_management.score)" } } }, "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "last_updated": "2021-04-14T14:42:04.219025Z", "ref": "<RULE_REF>" } ], "last_updated": "2021-04-14T14:42:04.219025Z", "phase": "http_response_headers_transform" }, "success": true, "errors": [], "messages": []
}
Example: Add a set-cookie HTTP response header with a static value
The following example configures the rules of an existing phase ruleset ({ruleset_id}) to a single HTTP response header modification rule — adding a set-cookie HTTP response header with a static value — using the Update a zone ruleset operation. By configuring the rule with the add operation you will keep any existing set-cookie headers that may already exist in the response.
Requestcurl --request PUT \https://api.cloudflare.com/client/v4/zones/{zone_id}/rulesets/{ruleset_id} \
--header "Authorization: Bearer <API_TOKEN>" \
--header "Content-Type: application/json" \
--data '{ "rules": [ { "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "action": "rewrite", "action_parameters": { "headers": { "set-cookie": { "operation": "add", "value": "mycookie=custom_value" } } } } ]}'
The response contains the complete definition of the ruleset you updated.
Response{ "result": { "id": "<RULESET_ID>", "name": "Zone-level Response Headers Transform Ruleset", "description": "Zone-level ruleset that will execute Response Header Modification Rules.", "kind": "zone", "version": "2", "rules": [ { "id": "<RULE_ID>", "version": "1", "action": "rewrite", "action_parameters": { "headers": { "set-cookie": { "operation": "add", "value": "mycookie=custom_value" } } }, "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "last_updated": "2021-04-14T14:42:04.219025Z", "ref": "<RULE_REF>" } ], "last_updated": "2021-04-14T14:42:04.219025Z", "phase": "http_response_headers_transform" }, "success": true, "errors": [], "messages": []
}
Example: Remove an HTTP response header
The following example sets the rules of an existing phase ruleset (<RULESET_ID>) to a single HTTP response header modification rule — removing an HTTP response header — using the Update a zone ruleset operation:
Requestcurl --request PUT \https://api.cloudflare.com/client/v4/zones/{zone_id}/rulesets/{ruleset_id} \
--header "Authorization: Bearer <API_TOKEN>" \
--header "Content-Type: application/json" \
--data '{ "rules": [ { "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "action": "rewrite", "action_parameters": { "headers": { "cf-connecting-ip": { "operation": "remove" } } } } ]}'
The response contains the complete definition of the ruleset you updated.
Response{ "result": { "id": "<RULESET_ID>", "name": "Zone-level Response Headers Transform Ruleset", "description": "Zone-level ruleset that will execute Response Header Modification Rules.", "kind": "zone", "version": "2", "rules": [ { "id": "<RULE_ID>", "version": "1", "action": "rewrite", "action_parameters": { "headers": { "cf-connecting-ip": { "operation": "remove" } } }, "expression": "(starts_with(http.request.uri.path, \"/en/\"))", "description": "My first HTTP response header modification rule", "last_updated": "2021-04-14T14:42:04.219025Z", "ref": "<RULE_REF>" } ], "last_updated": "2021-04-14T14:42:04.219025Z", "phase": "http_response_headers_transform" }, "success": true, "errors": [], "messages": []
}
Required API token permissions
The API token used in API requests to manage HTTP response header modification rules must have at least the following permissions:
- Transform Rules > Edit
- Account Rulesets > Read