Daniel Nashed's Blog

Introducing DomProbe – The Missing Piece for Prometheus NRPC Monitoring

The Prometheus ecosystem already provides excellent monitoring components.
The standard Blackbox Exporter is perfect for probing HTTP, HTTPS, TCP, ICMP and many other network protocols, while exporters such as node_exporter and DomProm provide detailed operating system and Domino server metrics.
But there has always been one missing piece: Native NRPC monitoring for HCL Domino.
That's exactly why I created DomProbe.

Why NRPC Monitoring Matters

Many critical Domino functions depend on NRPC: Notes client connectivity, replication, clustering, administration, mail routing, and server-to-server communication.
A Domino server may still answer HTTPS requests while NRPC is no longer functioning correctly. Likewise, a simple TCP connection to port 1352 only tells you that something is listening—it does not confirm that Domino is actually able to process NRPC requests.
DomProbe performs a real NRPC transaction using the native Domino C API. It connects to the target server, measures request and response latency, reports the Domino server state, and can optionally verify that a specific database can be opened.
This provides a much more meaningful availability check than simply testing whether port 1352 is open.


A Natural Extension to the Prometheus Ecosystem

DomProbe follows the same architecture as the Prometheus Blackbox Exporter.
Prometheus sends an HTTP request to DomProbe, which performs the NRPC probe and returns the results in standard Prometheus metrics format.
Existing Prometheus and Grafana dashboards, alert rules, and scrape configurations work exactly as expected—the only difference is that the probe itself understands Domino.
Typical metrics include:

• NRPC availability
• Domino server state (Available, Restricted, Busy, Not Reachable)
• Client-to-server latency
• Server-to-client latency
• Total probe duration
• Optional database open verification and timing

Combined with DomProm and node_exporter, this finally completes the monitoring stack for Domino environments.

Monitor Your Entire Domino Infrastructure

Although DomProbe runs as a native Domino server task on Linux, it is not limited to probing the local server.
A single DomProbe instance can probe any Domino server reachable via NRPC.
For example, you might deploy one DomProbe instance in each data center:

• A Domino server in Data Center A probes all production servers in its own site as well as selected servers in Data Center B.
• Another Domino server in Data Center B performs the same checks in the opposite direction.

This verifies much more than whether the target servers are running. It also confirms that NRPC communication between Domino servers is actually working.
Routing problems, firewall issues, VPN failures, or replication connectivity problems become immediately visible from the perspective of another Domino server.
Since Prometheus simply calls the /probe endpoint with different target parameters, a single DomProbe instance can monitor dozens or even hundreds of Domino servers without requiring additional software on every monitored system.

Lightweight by Design

DomProbe intentionally focuses on availability monitoring.
It does not try to replace detailed monitoring solutions such as DomProm or node_exporter.

Instead, the components complement each other:

• Prometheus Blackbox Exporter — HTTP, HTTPS, TCP, ICMP, DNS and other standard protocols
• DomProbe — Native Domino NRPC availability and optional database access
• DomProm — Domino server statistics, replication, mail routing, performance and health metrics
• node_exporter — Operating system metrics

Together they provide a complete monitoring solution for HCL Domino.

Native Domino Integration

DomProbe runs as a native Domino server task on Linux and integrates directly with the Domino runtime using the Domino C API.
The task exposes familiar Prometheus endpoints such as /probe, /metrics, and /health, making integration with existing Prometheus environments straightforward.


Open Source


DomProbe closes one of the last remaining gaps in the Prometheus monitoring ecosystem for HCL Domino by bringing native NRPC probing to Prometheus.
If you're already using Prometheus and Grafana to monitor your Domino infrastructure, DomProbe adds the missing visibility into the protocol that powers Domino itself.

https://github.com/nashcom/domino-blackbox-exporter
Comments Disabled