Service Mesh (Istio, Linkerd, Envoy)

Imagine you're building an e-commerce application using microservices. Your system has several independent services, including the Order Service, Payment Service, Inventory Service, and Notification Service.

These services frequently communicate with one another. For example, when a customer places an order, the Order Service might call the Inventory Service to reserve products and the Payment Service to process the payment.

Initially, each service handles its own network communication. But as your application grows, you start encountering common challenges.

How do you securely authenticate communication between services? How do you apply consistent timeout and retry policies? How do you monitor requests that travel through multiple microservices? How do you gradually roll out a new service version without changing application code?

One approach is to implement these capabilities inside every microservice. However, this leads to duplicated infrastructure logic, inconsistent implementations, and additional maintenance.

A Service Mesh addresses these problems by moving many service-to-service communication responsibilities into a dedicated infrastructure layer.