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
已提問 9 個月前檢視次數 446 次
1 個回答
2
已接受的答案

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
專家
已回答 9 個月前
  • Thank you, Very Explanatory Resource

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