Feature request: Fn::ForEach support for generating array items (not just resources)

[singledigit]

Description

Community feedback from the Language Extensions blog post:

Fn::ForEach currently generates top-level resources, conditions, and outputs. However, developers also need to generate array items within a resource property from a collection.

Use Case

DynamoDB tables have several array-typed properties (e.g., AttributeDefinitions, GlobalSecondaryIndexes, ReplicaUpdates) where each item follows the same structure but varies by a key value. Currently, these must be manually listed even when a parameter provides the collection.

Example (desired behavior):

Parameters:
  Attributes:
    Type: CommaDelimitedList
    Default: "id,name,email"

Resources:
  MyTable:
    Type: AWS::DynamoDB::Table
    Properties:
      AttributeDefinitions:
        Fn::ForEach::Attrs:
          - AttrName
          - !Ref Attributes
          - AttributeName: !Sub ${AttrName}
            AttributeType: S

Current Workaround

Users maintain custom CloudFormation macros: https://github.com/mlhpdx/cloudformation-macros

Source

Comment by Lee Harding on AWS Builder Center blog post, May 2026.

Related

• feat: Add CloudFormation Language Extensions support (Fn::ForEach) #8637 (Language Extensions support PR)
• Feature request: Support LanguageExtensions feature Fn::ForEach #5647 (original Fn::ForEach request)