On-prem monitoring —
monitor what cloud SaaS can't see

Who runs infrastructure cloud monitoring can't reach

Plenty of production infrastructure never gets a public IP, and not by accident. Banks and payment processors keep core systems on private networks because a regulator expects it. Hospitals run clinical systems on-prem because patient data cannot leave the building. Government and defence work inside segmented or air-gapped networks by mandate. Manufacturers run plant-floor systems and SCADA on isolated subnets.

None of these teams chose their topology to make monitoring hard — they chose it for data residency, isolation or compliance. The result is the same: the systems that matter most are the ones a public-internet probe physically cannot test.

What on-prem teams actually need to watch

The public website is usually the best-monitored thing a company owns. The systems behind it are not:

• Legacy line-of-business systems — the ERP installed in 2011, the billing system nobody wants to touch. They rarely have health endpoints; a TCP check that the port is open is often the only signal available, and it is enough.
• Internal databases — the on-prem Postgres or Oracle instance the whole application tier depends on. When it stops accepting connections, every downstream service degrades.
• Internal admin panels and tools — the ticketing system, the internal wiki, the deployment dashboard. Staff-facing, so an outage is invisible to public monitoring but very visible to the people trying to work.
• Staging and pre-production — environments that gate releases. If staging is down and nobody knows, the release pipeline is quietly stuck.
• On-prem CI runners and build infrastructure — when these stall, every team's deploy slows down at once.

Where cloud-only monitoring falls short

Pingdom, Datadog Synthetics, UptimeRobot and similar tools are built around probes that live on the public internet. That model works well for a public website. For a private subnet it leaves two bad options.

The first is to expose the internal service — a public load balancer, a port-forward, an inbound firewall rule — so the cloud probe can reach it. That trades a monitoring gap for an attack surface, and a security review will rightly push back on it.

The second is the vendor's enterprise on-prem agent, which usually sits behind a higher pricing tier and a sales conversation. Teams end up running a cloud SaaS for the public site and a separate self-hosted stack — Nagios, Zabbix, a Prometheus blackbox setup — for everything internal. Two tools, two alert pipelines, two on-call configurations, and no single view when a hybrid app breaks across the boundary.

One tool for public and on-prem, one bill

Status Harbor probes public endpoints from 9 regions and probes on-prem systems with a lightweight agent that runs inside your network. Both report to the same dashboard, raise incidents through the same pipeline and alert on the same channels — Slack, Telegram, email or webhook.

The agent makes a single outbound HTTPS connection and accepts nothing inbound, so it fits an egress-only security posture without firewall changes or a VPN. That outbound-only design — and exactly how the agent reaches services behind a firewall — is covered in detail on the private network monitoring page.

For a hybrid system — a cloud frontend in front of an on-prem database — you see the whole path in one place instead of stitching together two monitoring tools after the fact.

Frequently asked questions

Related

• Private network monitoring — the technical detail of how the agent reaches services behind a firewall.
• Kubernetes monitoring — monitor private clusters, including on-prem and self-managed ones.
• Monitoring as code with Terraform — manage on-prem monitoring agents alongside the rest of your infrastructure.