After making major changes to a Deployment Manager template, how do you get the fastest feedback that resource dependencies are satisfied before applying the change to the project?

The --preview flag for Deployment Manager allows you to see the planned changes without actually applying them, providing immediate feedback on whether resource dependencies are satisfied and if the deployment would succeed. This is the fastest and safest way to validate your template before making actual changes to your project. Adding granular logging statements is reactive and only helps after a failure, not before. Monitoring Cloud Logging is also reactive, showing execution details after the fact. Executing against a separate project adds unnecessary overhead and time, and might not perfectly mirror the production environment's state or quotas.