The AWS CloudFormation Stack Diagnostics skill automates troubleshooting of failed CloudFormation stack deployments. It uses the AWS CLI commands aws cloudformation describe-stack-events to trace resource-level failure chains, aws cloudformation detect-stack-drift for drift detection, and aws cloudformation get-template to retrieve deployed templates for comparison.

The skill integrates with cfn-lint (cloudformation-linter) for template validation against AWS CloudFormation Resource Specification, catching errors before deployment. It validates both JSON and YAML templates, checks resource property types against provider schemas, and verifies IAM policy document syntax.

Diagnostic workflows include stack event timeline analysis to identify the root cause resource in creation/update failures, rollback trigger identification through ROLLBACK_IN_PROGRESS event tracing, nested stack failure propagation tracking via parent-child stack relationships, and change set analysis using aws cloudformation describe-change-set for safe update previewing.

Advanced capabilities include custom resource (AWS::CloudFormation::CustomResource) Lambda log correlation via CloudWatch Logs Insights queries, stack policy analysis for update protection verification, resource import feasibility checking for brownfield adoption, and integration with AWS CloudFormation Guard (cfn-guard) for policy-as-code compliance validation against organizational rules.