Service mesh patterns with sidecar proxy

Need consistent observability, security, and traffic management across microservices without modifying application code.

Service mesh deploys a sidecar proxy alongside each service:

Architecture:

[Service A] <-> [Proxy A] <--network--> [Proxy B] <-> [Service B]
                    \                       /
                     \--- Control Plane ---/

What the sidecar handles:

• mTLS: Automatic encryption between services
• Retries/timeouts: Configurable per-route
• Circuit breaking: Prevent cascade failures
• Load balancing: Client-side, multiple algorithms
• Observability: Metrics, traces, access logs for free
• Traffic splitting: Canary deployments, A/B testing

When to use a service mesh:

• 10+ microservices
• Need consistent security policies
• Multiple teams deploying independently
• Complex traffic routing requirements

When NOT to use:

• Fewer than 5 services
• Monolith or simple architecture
• Team can't operate the complexity
• Latency-critical paths (sidecar adds ~1ms)

Popular options: Istio (feature-rich), Linkerd (simple), Consul Connect (HashiCorp ecosystem).

Service meshes move cross-cutting concerns out of application code into infrastructure, providing consistency without code changes.

Microservice architectures needing consistent networking behavior