Service Mesh (Istio, Linkerd, Envoy)

As microservices grow, every service needs the same networking basics: timeouts, retries, circuit breakers, load balancing, encryption, and tracing.

Without a common layer, this logic gets duplicated across services and libraries, often with inconsistent behavior across teams and languages.

A service mesh moves this plumbing out of application code and into infrastructure, applying it uniformly across services.

This chapter covers sidecars, the data plane and control plane, libraries versus infrastructure, and when a service mesh is worth the added complexity.