---
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::Join:
            - ""
            - - !Sub "yum install ${myPackage}"
              - !Sub "yum install ${myAppPackage}"