Hybrid Cloud Apps with OpenShift and Kubernetes

Chapter 8. Working Example of Multicluster Application Delivery

Let’s take a look at a simple working example of a web application with a backing datastore. For our purposes, we will deploy an app that mimics the game PAC-MAN game from Atari. A user will interact with a dynamic frontend that stores information in a backing MongoDB.

We will deploy this application across multiple distinct clusters using the techniques discussed in Chapter 5. Each of the clusters will be provisioned from a hub running Open Cluster Management, as discussed in Chapter 6. Further, we will configure an external load balancer provided by a GSLB service hosted by F5. Incoming user requests will be routed from a global domain into one of the specific clusters. If any one of the clusters or the application experiences a problem, then user requests will no longer be routed to that cluster. We are going to go a little further and demonstrate how to integrate off-cluster resources like an F5 DNS Load Balancer Cloud Service, and we will integrate a ServiceNow change ticket into the example.

In Figure 8-1, we see our PAC-MAN application running on two OpenShift clusters with a load balancer routing traffic to app instances on either cluster. We can see the hub cluster with various resources that are helping to manage the overall system. Through the rest of this chapter, we will explain what these various parts are doing and provide a walk-through that you can do on your own to experiment with all of the moving ...