Istio is the first service mesh implementation that works by injecting Envoy as a sidecar proxy alongside each microservice. The sidecar intercepts all of the service's traffic and handles it more intelligently than a simple L3/L4 network does. A mesh of sidecars constitutes the data plane in which each microservice has its own sidecar as a proxy. The control plane manages and coordinates the work of the sidecars through a set of central components. Overall, the service mesh is an abstract layer on top of applications to handle service-to-service communication.

In this chapter, we will understand the architecture of Istio from the perspective of the control plane to look at its features and functions. We will see how the control plane, through policies and configurations, manages the proxies running in a data plane. By the end of this chapter, you will have a good understanding of Istio, which will be very helpful as we go about performing hands-on experiments in the upcoming chapters.

In this chapter, we will cover the following topics:

• Control plane
• Data plane
• Observability features