Auto-Scaling is the ability for the Google Compute Engine to scale up or down dependent on a health policy. The most common use is to scale up when demand on a server spikes up.
The Policies that define Autoscaling healthchecks are:
- Average CPU utilization
- HTTP load balancing service capacity
- Max CPU
- Max requests per second
- Stackdriver standard and custom metric
Auto-scaling requires a load balancer configured and an instance group of Virtual machines. Consider the instant group like a template GCP uses to spin up additional servers.
To make Auto-Scaling work, you must
- Prep your image with boot sequence and software needed
- Define your auto scaler policy (Scale Out or Scale In)
For further information on Autoscaling check the Google Documentation.