first version of the knowledge base :)

70 - Tools/prometheus/prometheus.md

@@ -0,0 +1,63 @@
+---
+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/)