Service Mesh – Traffic Management, Observability, and Security

What Is a Service Mesh?

A service mesh is a dedicated infrastructure layer that handles service-to-service communication.
It works without modifying your application code.

In a mesh, each service talks to a sidecar proxy, which manages:

• Routing
• Authentication
• Observability
• Retries and timeouts

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Why Use a Service Mesh?

Microservices bring flexibility—but they also introduce complexity:

• Debugging is harder
• Communication failures are silent
• Security between services is non-trivial

A service mesh solves these problems by offering:

• Uniform policies
• Metrics and tracing
• Encryption with mTLS
• Traffic shaping (canary, failover, etc.)

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Sidecar Proxy Pattern

Each service instance runs alongside a small proxy (like Envoy):

Service A ─┐
           ├─> Envoy Proxy ─> Network
           └<─ Envoy Proxy <─

All incoming/outgoing traffic is handled by the proxy.
This allows:

• Zero changes to app code
• Full control of communication behavior

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Key Features of Service Meshes

✅ Traffic Routing & Control

• Weighted routing (canary deployments)
• Retries, timeouts, circuit breakers

✅ Observability

• Tracing (Jaeger, Zipkin)
• Metrics (Prometheus)
• Logging

✅ Security

• Automatic mTLS between services
• Policy enforcement
• Access control

✅ Resilience

• Retry, failover, connection pooling
• Rate limiting, bulkhead isolation

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Popular Service Mesh Tools

Tool	Highlights
Istio	Feature-rich, built on Envoy, widely used
Linkerd	Lightweight, simple, fast to adopt
Consul Connect	Integrates with Consul for service discovery
Kuma	Built by Kong, flexible with Kubernetes/VMs

All integrate well with Kubernetes.

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Do You Really Need One?

Maybe not yet.
Start without a mesh unless:

• You have dozens of services in production
• You’re struggling with observability and traffic control
• You need advanced routing, retries, or mTLS

Mesh = added complexity, added power. Don’t adopt prematurely.

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Summary

A service mesh like Istio or Linkerd provides visibility, control, and security across your services — without modifying app code. It’s powerful, but should be introduced when your scale justifies it.

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Next up:
Lesson 09 – Securing Microservices: Authentication, Authorization, and mTLS