Nexus 3 has metrics information available in the administration support UI.
Additionally, Nexus 3.0.1 exposes the following REST endpoints for monitoring:
These require authentication, and the user must either be an administrator, or have the "nx-metrics-all" privilege.
curl -u admin:admin123 http://localhost:8081/service/metrics/ping
curl -u admin:admin123 http://localhost:8081/service/metrics/healthcheck