What is the best solution for Formating Templatebody in JSON for StackSets?

Question

I am trying to convert a regular CloudFormation Template to  a stackset.

I need to deploy IAM permissions, mainly roles in multiple accounts.

Issue I'm having is the proper way to convert the IAM roles.I have in my existing CloudFormation to the stackset.

I was informed I had to put the old CloudFormation template inside the  **Templatebody** of the CloudFormation Stack below; however, the format is not the same inside TemplateBody as it is in the original CF set. Is there some tool or better solution I can use to achieve this? If I type this out manually there's much room as the original CF template without stackset is 549 lines.

Here's an example of my StackSet template I have now.

{
    "MyStackSet}": {
        "Type": "AWS::CloudFormation::StackSet",
        "DeletionPolicy": "Retain",
        "Properties": {
            "StackSetName": "ReadAndWriteRoles",
            "Description": "IAM Read and Write",
            "PermissionModel": "SELF_MANAGED",
            "ManagedExecution": {
                "Active": true
            },
            "Tags": [
                {
                    "Key": "tag1",
                    "Value": "value1"
                }
            ],
            "TemplateBody": "{
  "AWSTemplateFormatVersion": "2010-09-09",
 "Resources": {
    "PrismaCloudRole": {
      "Type": "AWS::IAM::Role"
    }
  }
}
"
        }
    }
}

Any suggestions to achieve this?

Answer

Hello.

I think there is also a way to upload the original CloudFormation template to S3 and specify it with the S3 URL instead of embedding it with "TemplateBody".  
You can use the CloudFormation template in S3 as is by using the parameter "TemplateURL".  
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-cloudformation-stackset.html#cfn-cloudformation-stackset-templateurl

What is the best solution for Formating Templatebody in JSON for StackSets?

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