Stop Your Bad Lambda Deployments Before They Hit Production

When a CI/CD pipeline shows green but a Lambda deployment is broken in production, the root cause is often configuration issues that unit and integration tests miss. Using Lambda aliases and versions together with AWS CodeDeploy and CloudWatch alarms enables safer canary-style rollouts. A pre-traffic hook — a separate Lambda function invoked by CodeDeploy before shifting traffic — can proactively test the new version with realistic payloads and automatically trigger a rollback if anything fails. The full setup is demonstrated using AWS CDK with .NET, showing how a missing environment variable causes the pre-traffic hook to catch the bad release before any real traffic is affected.