How we can Monitor Resource Changes In Google Cloud and how to monitor for GCP resource changes, automate alerts based on those changes and invoke an action.
There is a complete Operation Suite(formerly known as Stackdriver) on Google Cloud Platform that provides the features mentioned above.
Official documentation: https://cloud.google.com/products/operations
Cloud Monitoring, Cloud Alerting can be used to alerts based on different events. Alerts can be published to different channels like email, slack, etc.