You need to test an App Engine update with production traffic before replacing the current version. What should you do?

The correct approach is to deploy the update as a new version within the existing App Engine service and then use App Engine's built-in traffic splitting feature. This allows you to gradually route a percentage of incoming requests to the new version, effectively performing a canary release. If issues arise, you can easily roll back by adjusting the traffic split. Deploying with Instance Group Updater is incorrect because App Engine Standard and Flexible environments manage instances automatically; you don't directly interact with instance groups for version updates. Deploying in a separate VPC or as a new App Engine application and using global HTTP load balancing is overly complex and unnecessary. App Engine's native traffic splitting is designed precisely for this scenario, offering a simpler and more integrated solution for testing new versions with production traffic.