Provisioning a MIG and global load balancer

Note

The code for this section is under the chap06/main directory in the GitHub repository of this book.

To create a MIG, we first create an instance template, and then the MIG, which uses the instance template. The instance group is analogous to creating a virtual machine. Please note that we specify the service account we created and set the scopes to cloud-platform. That follows Google Cloud best practices: https://cloud.google.com/compute/docs/access/service-accounts#scopes_best_practice.

Now, here, we can put the create_before_destroy life cycle rule to good use. Let’s say we want to change the instance template by, for example, changing the startup script. Usually, Terraform destroys the google_compute_instance_template resource before applying the change and creating a new resource. However, Google Cloud won’t let us destroy google_compute_instance_template because the MIG still uses it. Hence, we use the create_before_destroy...