​​Loops in CloudFormation: !ForEach 💪

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-foreach.html

AWSTemplateFormatVersion: 2010-09-09
Transform: 'AWS::LanguageExtensions'
Resources:
'Fn::ForEach::Tables':
- TableName
- [Points, Score, Name, Leaderboard]
- 'DynamoDB${TableName}':
Type: 'AWS::DynamoDB::Table'
Properties:
TableName: !Ref TableName
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: '5'
WriteCapacityUnits: '5'

Fn::ForEach can be used in the sections:

▫️ Resource
▪️ Resource properties
▫️ Conditions
▫️ Outputs

Fn::ForEach parameters

Identifier (String) → Identifier is used to refer to the current element we’re iterating over within the Collection (Array of Strings).

Collection (Array of Strings) → Array of values that the Identifier can take.

OutputKey (String) → The key of the resulting key-value pair for the given element in the collection that will be merged to the parent object.

OutputValue (Any) → The value of the resulting key-value pair for the given element in the collection that will be merged to the parent object.

Note: the syntax of Fn::ForEach declaration has a suffix where the UniqueLoopName is used to identify the loop. This allows multiple Fn::ForEach function references to be declared on a given level.

#CloudFormation