Question

A DevOps team manages a large CloudFormation parent stack that references three nested stacks (network, application, and database). During a recent update to modify an Auto Scaling group configuration in the application nested stack, the update failed and the entire deployment rolled back — including unrelated resources in the network nested stack that had already succeeded. The team wants to reduce the blast radius so that a failure in one nested stack's update does not force a rollback of resources in the other nested stacks, while still managing everything as a cohesive infrastructure set. What is the MOST appropriate approach?

Accepted Answer

Refactor the nested stacks into independent standalone stacks and use cross-stack references (Exports/Fn::ImportValue) to share values between them, deploying each stack independently.

Answer

Enable a stack policy on the parent stack that denies updates to the network nested stack resources so they cannot be rolled back.

Answer

Set the DisableRollback option to true on the parent stack update so no resources are ever rolled back on failure.

Answer

Add a DeletionPolicy of Retain to all resources in the network nested stack so they survive the rollback.