Real-World Example

Although everything we've learned so far is cool and interesting, the important questions are: How does it bring value? and How does it keep businesses running and make them more agile and resilient?

Let's take a minute to run through a common real-world example – making updates to applications.

We all know that updating applications is a fact of life – bug fixes, new features, and more.

Figure 6.9 shows a simple application deployed on a Kubernetes cluster as a bunch of Pods managed by a Deployment. As part of it, we've got a Service selecting on Pods with labels that match app=biz1 and zone=prod (notice how the Pods have both of the labels listed in the label selector). The application is up and running:

Figure 6.9: Application managed by a deployment

Let's assume we need to push a new version. But we need to do it without incurring downtime.

To do this, we can add Pods running the new version...