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kloudformation

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Join

In CloudFormation you can concatenate Strings and intrinsic functions using Fn::Join

Info of Fn::Join from AWS can be found here

We have simplified how this works in KloudFormation by providing the plus operator.

You can concatenate any Reference, Value<String> or Attribute as follows:

val sgName = parameter<String>("Name")
securityGroup(groupDescription = +"Description-" + sgName.ref() + "-XYZ")

Tip: If the first element is a String then you need the unary plus to make it Value<String>

Produces

  SecurityGroup:
    Type: "AWS::EC2::SecurityGroup"
    Properties:
      GroupDescription:
        Fn::Join:
        - ""
        - - "Description-"
          - Ref: "Name"
          - "-XYZ"

By default the plus operator will create an instance of Join and will apply no splitter between elements.

If you want to supply a splitter you will need to create an instance of Join:

securityGroup(groupDescription = Join("-", listOf(+"Description", sgName.ref(), +"XYZ")))