Prometheus
Prometheus is an open-source monitoring and alerting toolkit that collects time-series metrics from applications and infrastructure, queried through its own PromQL query language.
Definition
Prometheus is an open-source monitoring and alerting toolkit that collects time-series metrics from applications and infrastructure, queried through its own PromQL query language.
Overview
Originally built at SoundCloud and later donated to the Cloud Native Computing Foundation, Prometheus has become the de facto standard for metrics collection in cloud-native and Kubernetes environments. It works on a pull model: rather than applications pushing metrics to a central server, Prometheus periodically scrapes HTTP endpoints exposed by instrumented applications and infrastructure components, storing the results as time-series data with labeled dimensions. PromQL, Prometheus's query language, lets operators aggregate, filter, and compute derived metrics — such as request rate, error percentage, or resource saturation — directly against the stored time series, powering both dashboards and alerting rules. Alertmanager, a companion component, handles deduplication, grouping, and routing of alerts generated from these rules to channels like Slack, email, or PagerDuty. Prometheus is almost always paired with Grafana for visualization, since Prometheus itself focuses on collection, storage, and querying rather than dashboarding. It also integrates with OpenTelemetry as one of many compatible metrics backends, and remains a core skill for anyone working in DevOps or site reliability engineering, commonly covered in courses like CI/CD with GitHub Actions that touch on production observability.
Key Features
- Pull-based metrics scraping from instrumented applications and services
- Multi-dimensional time-series data model with labeled metrics
- PromQL query language for aggregation and alerting logic
- Alertmanager component for routing and deduplicating alerts
- Service discovery integrations for dynamic cloud-native environments
- Wide ecosystem of exporters for third-party systems (databases, hardware, etc.)
- CNCF graduated project with broad community and vendor support