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 Using AWS CloudFormation Macros to Perform Custom Processing on Templates.

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

Declaration

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

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

!Transform { "Name" : macro name, "Parameters" : {key : value, ... } }

Parameters

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.

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

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

The following example calls the AWS::Include transform, specifying that the location to retrieve a template snippet from is located in the RegionMap mapping, under the key us-east-1 and nested key s3Location.

{
   "Fn::Transform" : {
       "Name" : "AWS::Include",
       "Parameters" : {
           "Location" : {"Fn::FindInMap" : ["RegionMap", "us-east-1", "s3Location"] }
        }
    }
}

'Fn::Transform':
    Name: 'AWS::Include'
    Parameters: {Location: {'Fn::FindInMap': [RegionMap, us-east-1, s3Location]}}

Supported Functions

None. AWS CloudFormation passes any intrinsic function calls included in Fn::Transform to the specified macro as literal strings. For more information, see AWS CloudFormation Macro Function Interface.

On this page:

• Declaration
• Parameters
• Return Value
• Examples
• Supported Functions