One cloud virtual machine instance is fine, but we've seen at the very start of the book that the reasons for switching to the cloud can be summed up in two words: autohealing and autoscaling. One cloud VM instance is not going to provide autohealing or autoscaling, so we need a higher-level abstraction, the Managed Instance Group (MIG).
Understanding this one sentence is really important, so let's parse it carefully.
That fundamentally is what a Managed Instance Group is. Each element in MIG is GCE VM, just like any other GCE VM that you might have spun up. One VM instance is vulnerable; it can crash or be overwhelmed by a spike in client traffic, but a group of VM instances is effectively a cluster and much more robust.
All the VM instances in an MIG are cast from the same mold; that mold is called an instance template. How does an instance...