Fn::Transform

The intrinsic function Fn::Transform specifies a macro to perform custom processing on part of a stack template. Macros enable you to perform custom processing on templates, from simple actions like find-and-replace operations to extensive transformations of entire templates. For more information, see Perform custom processing on CloudFormation templates with template macros.

You can also use Fn::Transform to call the AWS::Include transform transform, which is a macro hosted by AWS CloudFormation.

Declaration

JSON

Syntax for the full function name:

{
    "Fn::Transform": {
        "Name": "macro name",
        "Parameters": {
            "Key": "value"
        }
    }
}

Syntax for the short form:

{
    "Transform": {
        "Name": "macro name",
        "Parameters": {
            "Key": "value"
        }
    }
}

YAML

Syntax for the full function name:

Fn::Transform:
  Name : macro name
  Parameters :
    Key : value

Syntax for the short form:

!Transform
  Name: macro name
  Parameters:
    Key: value

Parameters

Name

The name of the macro you want to perform the processing.

Parameters

The list parameters, specified as key-value pairs, to pass to the macro.

Return value

The processed template snippet to be included in the processed stack template.

Examples

The following example calls the AWS::Include transform, specifying that the location to retrieve a template snippet from is passed in the InputValue parameter.

JSON

{
    "Fn::Transform": {
        "Name": "AWS::Include",
        "Parameters": {
            "Location": {
                "Ref": "InputValue"
            }
        }
    }
}

YAML

'Fn::Transform':
  Name: 'AWS::Include'
  Parameters:
    Location: !Ref InputValue

Supported functions

None.

CloudFormation passes any intrinsic function calls included in Fn::Transform to the specified macro as literal strings. For more information, see CloudFormation macro function interface.