Backend & systems·Deployment, release and rollback
you get mutual TLS, retries and per-route traffic splitting without changing a line of application code, because a proxy sits next to each instance.
Service mesh
Also calledsidecar proxy, Envoy, Istio
A layer of proxies deployed alongside services, handling routing, retries, mTLS and telemetry uniformly. It moves cross-cutting concerns out of each service's language and libraries. The cost is a substantial amount of operational machinery and a new class of failures that look like application bugs but live in the proxy.