Mark Fischer

11 minute read

This article aims to demonstrate some of the many uses of the Fn::Sub syntax in the AWS CloudFormation service. Topics include:

  • Basic Fn::Sub and !Sub syntax
  • Short and long form syntax
  • Nested Sub and ImportValue statements


About a year ago (Sept 2016, along with YAML support) AWS added a new intrinsic function to CloudFormation: Fn::Sub. This greatly improved string concatenation in CloudFormation.