--- AWSTemplateFormatVersion: "2010-09-09" Description: > Test Sub Over Join Parameters: myPackage: Type: String Default: httpd Description: Web Package myAppPackage: Type: String Default: java Description: App Package Resources: myInstance: Type: AWS::EC2::Instance Properties: ImageId: String UserData: Fn::Base64: Fn::Sub: | yum install ${myPackage} yum install ${myAppPackage} myInstance2: Type: AWS::EC2::Instance Properties: ImageId: String UserData: Fn::Base64: Fn::Join: - "" - - Fn::Select: - 0 - Fn::Split: - "/" - "a/path/" - !Sub "yum install ${myAppPackage}"