Skip to content

CloudFormation Intrinsic Functions

Links: 102 AWS DVA Index


  • Fn::Ref
  • YAML short hand !Ref
  • If we refer parameters it returns the value of the parameter
  • If we refer resources it returns the physical ID of the underlying resource (ex: EC2 ID)


  • Fn:GetAtt
  • Attributes are attached to any resources you create
  • We can get a lot of attributes depending on the resource. To know what is exposed by the resource we will have to go through the documentation.
    • attachments/Pasted image 20220518155349.jpg
    • attachments/Pasted image 20220518155530.jpg


  • Accessing map values
  • Fn::FindInMap to return a named value from a specific key.
  • Another notation !FindInMap [MapName, TopLevelKey, SecondLevelKey]


  • Import values that are exported In other templates
  • Fn:ImportValue


  • Fn::Join
  • To create a:b:c we can use !Join [":",[a, b, c]]


  • Fn::Sub
  • Fn::Sub, or !Sub as a shorthand, is used to substitute variables from a text. It's a very handy function that will allow you to fully customise your templates.
  • For example, you can combine Fn::Sub with references or AWS Pseudo variables
  • String must contain ${VariableName} and will substitute them.
    • attachments/Pasted image 20220518160148.jpg

Last updated: 2022-06-09