4. Building scalable applications

When running an application, the ability to scale and upgrade your application is critical. Scaling is required to handle additional loads with your application, while upgrading is required to keep your application up to date and to be able to introduce new functionality.

Scaling on demand is one of the key benefits of using cloud-native applications. It also helps optimize resources for your application. If the front-end component encounters heavy loads, you can scale the front end alone, while keeping the same number of back-end instances. You can increase or reduce the number/size of Virtual Machines (VM) required depending on your workload and peak demand hours. This chapter will cover both the scale dimensions in detail.

In this chapter, we will show you how to scale the sample guestbook application that we introduced in Chapter 3, Application deployment on AKS. We will first scale this application using manual commands, and afterward...