Prometheus

Prometheus is an open-source systems monitoring and alerting toolkit designed for reliability, scalability, and observability in modern infrastructure. It collects metrics as time series data, identified by metric name and key-value labels, enabling a highly dimensional data model for fine-grained analysis. Prometheus uses a pull-based model, scraping metrics from instrumented targets via HTTP, which simplifies configuration, supports service discovery, and reduces the need for external agents.

A core component is PromQL, a powerful and flexible query language that allows users to aggregate, filter, and transform time series data for dashboards, ad-hoc analysis, and capacity planning. Data is stored in an efficient, custom time series database optimized for high ingestion rates and fast queries, with support for recording rules to precompute frequently needed aggregations.