Hands-On Microservices with Kubernetes

Routing requests

Istio introduces its own virtual services as a CRD. Istio services have a concept of a version that doesn't exist for Kubernetes services. The same image can be deployed as different versions of a virtual service. For example, you can represent the production or staging environment as different versions of the same service. Istio allows you to configure rules that determine how to route traffic to different versions of a service.

The way this works is that Pilot sends ingress and egress rules to the proxies that determine where requests should be handled. You then define the rules as a CRD in Kubernetes. Here is a simple example that defines a virtual service for the link-manager service:

apiVersion: networking.istio.io/v1alpha3 ...