Cloud Formation Functional Validation

Hi Eli,

Please Try this solution it will be helpfull for you and also follow aws documentation link you will get more information.

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-validate-template.html#:~:text=During%20validation%2C%20AWS%20CloudFormation%20first%20checks%20if%20the,--template-body%20parameter%2C%20or%20remotely%20with%20the%20--template-url%20parameter.

Install AWS CloudFormation Guard: AWS CloudFormation Guard is a policy-as-code tool that allows you to define rules to validate your CloudFormation templates. Install it using npm:

npm install -g @aws-cloudformation/cloudformation-guard

Create Guard Rules: Define rules to validate the logical correctness of your templates. For example, to ensure a VPC resource has a CIDR block, create a file named vpc.guard with the following content:

rule vpc {   Resources.MyVPC.Properties.CidrBlock == /[0-9]{1,3}(\.[0-9]{1,3}){3}\/[0-9]{1,2}/ }

Validate the Template: Use the cfn-guard command to validate your CloudFormation template against the defined rules. Assume your template file is named template.yaml:

cfn-guard validate -r vpc.guard -t template.yaml

This will check if the VPC resource in your template has a valid CIDR block.

Use CloudFormation Change Sets: Before applying changes, use Change Sets to preview how the proposed changes might impact your stack. This helps catch logical errors that may not be evident from static analysis alone.

aws cloudformation create-change-set --stack-name my-stack --template-body file://template.yaml --change-set-name my-change-set

aws cloudformation describe-change-set --change-set-name my-change-set --stack-name my-stack