---
title: Prometheus
description: Tool overview for Prometheus as a metrics collection, query, and alerting platform
tags:
  - prometheus
  - monitoring
  - observability
category: tools
created: 2026-03-14
updated: 2026-03-14
---

# Prometheus

## Summary

Prometheus is an open source monitoring system built around time-series metrics, pull-based scraping, alert evaluation, and queryable historical data. It is a standard choice for infrastructure and service monitoring in self-hosted environments.

## Why it matters

Prometheus gives operators a consistent way to collect metrics from hosts, applications, and infrastructure components. It is especially valuable because it pairs collection, storage, and alert evaluation in one practical operational model.

## Core concepts

- Scrape targets and exporters
- Time-series storage
- PromQL for querying and aggregation
- Alerting rules for actionable conditions
- Service discovery integrations for dynamic environments

## Practical usage

Prometheus commonly fits into infrastructure as:

```text
Targets and exporters -> Prometheus -> dashboards and alerts
```

Typical uses:

- Scraping node, container, and application metrics
- Evaluating alert rules for outages and resource pressure
- Providing metrics data to Grafana

## Best practices

- Start with critical infrastructure and user-facing services
- Keep retention and scrape frequency aligned with actual operational needs
- Write alerts that map to a human response
- Protect Prometheus access because metrics can reveal sensitive system details

## Pitfalls

- Collecting too many high-cardinality metrics without a clear reason
- Treating every metric threshold as an alert
- Forgetting to monitor backup freshness, certificate expiry, or ingress paths
- Running Prometheus without a retention and storage plan

## References

- [Prometheus overview](https://prometheus.io/docs/introduction/overview/)
- [Prometheus concepts](https://prometheus.io/docs/concepts/)
- [Prometheus configuration](https://prometheus.io/docs/prometheus/latest/configuration/configuration/)