<strong>Service mesh</strong> is an infrastructure layer that handles service-to-service communication in microservices. It provides observability, security, and reliability without changing application code.
The Postal Service Analogy
Buildings don't deliver mail themselves. The postal service handles routing, tracking, and delivery. Service mesh does the same for service communication.
Buildings (Services)
Send/receive mail
Postal Service (Service Mesh)
Handles delivery
Letters (Requests)
Communication
Calls Service B
Manages Communication
Receives Request
Service A calls Service B
Request goes through sidecar proxy
Mesh handles routing
Load balance, retry, timeout logic
Mesh encrypts traffic
Mutual TLS between services
Mesh collects metrics
Track latency, errors, traffic
Mesh enforces policies
Rate limiting, access control
Wrong
"Service mesh is required for microservices"
Correct
<strong>Service mesh adds complexity</strong>. Only needed when you have many microservices and need advanced features like mTLS, traffic management, observability. Start simple.
100 microservices with Istio:
Without mesh: Each service implements retry, timeout, metrics (duplicated code)
With mesh: Istio handles all cross-cutting concerns
Automatic mTLS encryption between all services
Centralized traffic management and observability
Deploy new service → mesh features work automatically