cloudformation-best-practices

Use YAML with parameterized environment-specific values, Mappings for static lookups, and Conditions for multi-environment support. Add DeletionPolicy: Retain on stateful resources like RDS, S3, and DynamoDB, and validate with aws cloudformation validate-template before deploying.

Use Outputs with Export in the source stack and ImportValue in consuming stacks for cross-stack references. Name exports with !Sub and environment prefixes, such as ${Environment}-VpcId, to avoid collisions across environments.

This Skill applies only to raw CloudFormation templates in YAML or JSON. If your team prefers CDK or Terraform for infrastructure definition, those tools generate or manage resources differently and this guidance does not apply.

Run continue-update-rollback with the --resources-to-skip flag for the failing resource to unblock the stack. After the stack stabilizes, fix the root cause of the failure and redeploy the corrected template.

Use cfn-lint to catch template syntax and best-practice violations, and cfn-nag to detect security issues like overly permissive rules. Run both in CI alongside aws cloudformation validate-template before any deployment.