Prometheus

Prometheus is a monitoring system that scrapes time series metrics from endpoints on a schedule, stores them in an on-disk database, and evaluates alerting and recording rules against them. Its query language, PromQL, covers rates, histograms, and label based joins, and it pairs with service discovery for cloud and container platforms, exporters for databases, and remote write for long-term storage.

Teams use it as the source of truth for infrastructure metrics and to feed dashboards and on-call routing.

Running it on your own hardware keeps the metric history of your infrastructure private, avoids per-host SaaS costs, and makes the data directory straightforward to snapshot and restore.