Hosting a highly scalable application on Google Compute Engine

There are a number of ways to host a highly scalable application on GCP using Compute Engine, App Engine, and Container Engine. We'll look at a simple PHP and MySQL application hosted on GCE with Cloud SQL and see how the GCP ecosystem helps us in building it in a scalable manner.

First, we'll create a Cloud SQL instance, which will be used by the application servers. The application servers should be designed to be replicated at will depending on any events, such as CPU usage, high utilization, and so on.

So, we'll create an instance template which is a definition of how GCP should create a new application server when it is needed. We feed in the start up script that prepares the instance to our requirements.

Then, we create an instance group which is a group of identical instances defined by the instance template. The instance group also monitors the health of the instances to make sure they maintain the defined number of servers. It automatically identifies unhealthy instances and recreates them as defined by the template.

Later, we create an HTTP(S) load balancer to serve traffic to the instance group we have created. With the load balancer in place, we now have two instances serving traffic to the users under a single endpoint provided by the load balancer. Finally, to handle any unexpected load, we'll use the autoscaling feature of the instance group.