Which of the following is a lightweight tool that manages traffic flows between services, enforces access policies, and aggregates telemetry data, all without requiring changes to application code?

NetworkPolicy defines firewall rules for pod communication within Kubernetes but does not manage traffic flows, aggregate telemetry, or enforce detailed access policies like a service mesh.

Linkerd is a service mesh that operates by injecting proxies alongside application containers, transparently intercepting and managing inter-service communication. This design allows it to provide features like traffic management, security policies (e.g., mTLS), and rich telemetry without requiring any modifications to the underlying application code.

kube-proxy maintains network rules on nodes to enable Service abstraction but does not manage inter-service traffic flows, enforce higher-level access policies, or collect detailed telemetry like a service mesh.

Nginx is a popular web server and reverse proxy, often used as an Ingress controller, but it is not a service mesh that transparently manages all inter-service traffic, policies, and telemetry across a cluster without application changes.