CodeDeploy rollback alarm never fires because canary target group is missing

The blue-green deployment partially shifts traffic, but the rollback condition never triggers because the health alarm watches only the stable target group.

• Identify the primary failure signal in the Deployment Safety scenario.
• Separate visible symptoms from the underlying technical dependency.
• Describe the safest recovery path and the follow-up prevention work.

1. Summarize the current impact and the last known change.
2. Collect direct evidence from logs, runtime state, and configuration before changing anything.
3. Separate immediate recovery from permanent prevention work.

Choose the smallest safe recovery action first, then record the prevention work that reduces repeat incidents.