如果尚未创建新的SSM参数，如何创建AWS云形成条件？

Question

Anyone used condition in Cloudformation template for SSM Parameter Store parameter "if it is not created before then create or do nothing" like condition in Cloudformation ?

I have tried it in many ways but no luck. Also search for it but there is no real working thing around.

The simplest way I have tried outside of my real CF template is this but not working. There is no detailed documentation at the AWS Cloudformation part.

Parameters:
  DAXClusterUrl:
      Description: DAX Cluster Url
      Type: 'AWS::SSM::Parameter::Name<String>'
      Default: "/testservice/dev/AWS_CLUSTER_ENDPOINT"

Conditions:
  CreateDAXClusterUrlParameter: !Not [!Equals ["", !Ref DAXClusterUrl]]

Resources:
  DAXClusterUrlParameter:
    Condition: CreateDAXClusterUrlParameter
    Type: 'AWS::SSM::Parameter'
    Properties:
      Name: "/testservice/dev/AWS_CLUSTER_ENDPOINT"
      Type: String
      Value: "TestURL"
      Description: '-'

Answer 1

I don't think it is possible to do what you are trying here. Cloudformation only allows a very limited type of programming and conditional statements.

Depending on what you are trying to achieve, there are some workaround you can use. For example, if you are trying to do this, because you need to deploy the stack multiple times, you can either create the SSM parameter manually or in a different CFN stack and pass it as a parameter. Or, if you are creating the SSM parameter in a separate CFN stack anyway, you can add it to the outputs section of the template and then use the Fn::ImportValue method to create a cross-stack reference.

EDIT

After the comment by OP I did some more research and while the link that's in the comment only forces the value of the parameter to be a certain way, dynamic references might provide a solution here.