What is a Service Mesh?
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Quick Answer
A service mesh is a dedicated infrastructure layer (e.g., Istio, Linkerd) that manages service-to-service communication via sidecar proxies — providing mTLS, traffic routing, retries, and observability without changing app code.
Detailed Answer
Sidecars (or a sidecar-less dataplane) intercept traffic to enforce mutual TLS, fine-grained routing (canary, mirroring), timeouts/retries/circuit breaking, and rich telemetry, all controlled from a central control plane. The trade-off is added complexity and latency, so adopt it when you have enough services that these concerns justify it.
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Interview Tip
Name concrete features (mTLS, traffic shaping, retries, telemetry) and the complexity trade-off — meshes are powerful but not free.
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