Prometheus is the open-source standard for metrics in cloud-native systems, and understanding its model explains most of modern monitoring.
Prometheus is an open-source (CNCF) monitoring system and time-series database that collects metrics by scraping HTTP endpoints on a schedule, stores them as labelled time series, and lets you query them with PromQL. It is the de facto standard for metrics in cloud-native environments.
Prometheus uses a pull model: on an interval it scrapes a /metrics endpoint that each target exposes, and stores what it finds as time series identified by a metric name and labels. You query those series with PromQL, its query language, and route alerts through Alertmanager. For systems that do not expose Prometheus metrics natively, exporters translate their state into the format Prometheus can scrape. This simple, reliable model is why Prometheus became ubiquitous in Kubernetes.
Prometheus is metrics-only by design, while OpenTelemetry spans traces, metrics and logs. The two interoperate rather than compete: the OpenTelemetry Collector can scrape Prometheus endpoints, Prometheus can now ingest OTLP metrics, and remote-write lets Prometheus data flow into long-term stores. A common modern setup instruments with OpenTelemetry and stores metrics in a Prometheus-compatible backend, keeping PromQL for queries.
Prometheus earned its dominance for good reasons: a simple, reliable pull model, a powerful query language in PromQL, a huge ecosystem of exporters, and native fit with Kubernetes. Its limits are equally worth knowing. It is single-node by design, so high availability and long-term retention need additional systems. It handles high-cardinality labels poorly, because every unique label combination is a separate time series. And it is metrics-only, so it does not see traces or logs. Knowing both sides tells you when Prometheus is exactly right and when you need to complement it.
Prometheus is rarely used entirely alone. Grafana is the near-universal dashboard layer on top of it. For scale and long-term storage, projects like Thanos, Cortex and Grafana Mimir extend Prometheus into a highly available, multi-tenant, long-retention system that still speaks PromQL. Alertmanager handles alert routing and de-duplication. This ecosystem is part of why Prometheus is so entrenched: you can start with a single server and grow into a large, durable metrics platform without leaving the PromQL world your team already knows. That gravitational pull is why, even as OpenTelemetry standardises instrumentation, most teams still store and query their metrics in Prometheus or a Prometheus-compatible backend rather than replacing it.
Ops Singularity works with Prometheus-compatible metrics, so teams keep the Prometheus and PromQL knowledge they already have while TelemetryOps and Sentinel AI add correlation across signals and autonomous, governed resolution on top.
Yes. Prometheus is an open-source CNCF project. You self-host it (or use a managed compatible service); the software itself is free.
No. Prometheus is metrics-only. For traces and logs you use other tools, and OpenTelemetry is the common standard that spans all three signals.
Ops Singularity turns open telemetry into autonomous, governed resolution. See it on your own stack.