Reference Parameter Value in UserData in AWS Cloudformation - amazon-web-services

Question

I have this under parameter section ,
Parameters:
PlatformSelect:
Description: Cockpit platform Select.
Type: String
Default: qa-1
AllowedValues: [qa-1, qa-2, staging, production]
I need to reference this value in my UserData. I’m using Mappings in between.
Mappings:
bootstrap:
ubuntu:
print: echo ${PlatformSelect} >>test.txt
Resources:
EC2Instance:
Type: AWS::EC2::Instance
Properties:
InstanceType: !Ref ‘InstanceType’
KeyName: !Ref ‘KeyName’
Tags:
- Key: Name
Value: Test
UserData:
Fn::Base64:
Fn::Join:
- ‘’
- - |
#!/bin/bash
- Fn::FindInMap:
- bootstrap
- ubuntu
- print
- |2+
This is not working. Not sure the way I refer it is wrong in first place!!
Should I use something before it like, ‘${AWS::Parameters:PlatformSelect}’ ?

Answer 1

Is there a reason why you are using Mapping in between?
You could easily use !Sub instead
Resources:
EC2Instance:
Type: AWS::EC2::Instance
Properties:
InstanceType: !Ref InstanceType
KeyName: !Ref KeyName
Tags:
- Key: Name
Value: Test
UserData:
Fn::Base64:
!Sub |
#!/bin/bash
${PlatformSelect}

Answer 2

What about a combination of Fn::Join and Ref
UserData:
Fn::Base64:
Fn::Join:
- ''
- - '#!/bin/bash\n'
- 'print: echo'
- !Ref 'PlatformSelect'
- '>>test.txt\n'