Azure Deployment Stacks What-If reaches GA

What-If for Azure Deployment Stacks became generally available in all regions on August 18. The Azure Governance post says it previews changes to the stack and managed resources, including create, modify, delete, and detach. It works at resource-group, subscription, and management-group scope through CLI, PowerShell, and SDKs.

The preview is a durable resource

Standard deployment what-if returns an operation result. Stack What-If creates a named Microsoft.Resources/deploymentStacksWhatIfResults resource with a retention interval, so a pipeline can link reviewers to the same result it evaluated. Microsoft also uses the deployed stack’s baseline to filter noisy property differences.

Delete and detach deserve special attention because actionOnUnmanage can turn removing template declarations into destructive resource changes. A preview exposes that intent before deployment, but it still evaluates against a point-in-time state.

Make the artifact part of approval

On each infrastructure pull request, create a uniquely named result against the target stack and publish its resource ID with the code diff. Fail the pipeline on unsupported evaluation or unexpected delete and detach actions. Choose retention long enough for review and clean up results automatically.

Require a fresh evaluation when code or target state changes after approval. Limit permissions so contributors who propose a template cannot rewrite the approval evidence or deploy without the designated gate. Review deny-setting changes separately because they affect future control over managed resources.

Start with an existing nonproduction stack and compare predicted actions to an actual deployment. The feature improves visibility; it does not guarantee a provider will behave exactly as predicted under concurrent drift. Keep deployment activity logs and a recovery plan for stateful resources.