What is a Service Mesh? What problems does it solve in microservices architectures?

Service Mesh Concept

A service mesh is an infrastructure layer for service-to-service communication. It uses sidecar proxies (typically Envoy) to handle all network traffic between services, so business code doesn't need to worry about networking logic.

Core Problems It Solves

Observability: Automatically generates metrics, traces, and logs for all inter-service requests without code changes

Traffic management:

• Canary deployments: Route 10% of traffic to a new version
• Circuit breaking: Prevent cascading failures
• Retries and timeouts: Configure retry strategies consistently

Security:

• mTLS: Automatic mutual TLS encryption between services
• Authorization Policy: Fine-grained access control

Service discovery: Automatically discovers service endpoints in the cluster

Architecture

Data Plane: Sidecar proxies (Envoy) in each Pod

Control Plane: Manages and distributes configuration to all proxies

• Istio: istiod
• Linkerd: linkerd-control-plane

When You Need a Service Mesh

• Many microservices (>10), complex inter-service dependencies
• Need to enforce mTLS for security compliance
• Need fine-grained traffic control (A/B testing, progressive rollouts)

Trade-offs

Sidecar containers increase resource consumption per Pod (CPU/Memory), introduce additional network latency, and add configuration complexity.