Hands on GCP Deployment Manager
It's the structure of your deployment, where you define the name of the resources you want to deploy and its properties. Here is an example of a configuration file deploying a VM instance with Ubuntu 18.04 LTS on the default VPC network We declare a resource named , which is of type "compute.v1.instance" with its "properties" (zone, disks, network, etc,...).
https://medium.com/linkbynet/hands-on-gcp-deployment-manager-9db80122e29a