CloudFormation User Parameter as another parameter Default Value

0

Hello,

I keep getting this error

Template Format error parameter default has to be string and i want to use a Parameter as another Parameter Default.

Parameters:
  AppId:
    Type: String
    Default: "mygradecard-iac"
  RepositoryName:
    Type: String
    Default: !Sub "${AppId}-Respository"
    Description: "Name of the Repository to be Created"

Thank you

Nafiu
asked 8 months ago368 views
1 Answer
2
Accepted Answer

Hi,

You cannot do that so directly: as said by the message, a parameter is a string, you cannot call something like !Sub in a parameter defintion

But, there are solutions: I personally use SSM parameters to achieve what you want. See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ssm-parameter.html

BasicParameter:
    Type: AWS::SSM::Parameter
    Properties:
      Name: MyParam
      Type: String
      Value: 'xyz'
      Description: SSM Parameter for running date command.

In Value, you can use !Sub or any function.

Then, you obtain your value by calling !GetAtt MyParam.Value. Additional advantage, the SSM console will allow you to easily see the result of your value computation.

It works great for me. I wish that it will be same for you.

Best,

Didier

profile pictureAWS
EXPERT
answered 8 months ago
  • Thank you, Very Explanatory Resource

You are not logged in. Log in to post an answer.

A good answer clearly answers the question and provides constructive feedback and encourages professional growth in the question asker.

Guidelines for Answering Questions