What is Prometheus and how does its pull-based model differ from push-based monitoring?

Prometheus is an open-source metrics monitoring system with a time-series database.

Pull-based (Prometheus): Prometheus actively scrapes metrics from targets at regular intervals. Targets expose a /metrics HTTP endpoint. Benefits: Prometheus controls the scraping schedule, easy to detect if a target is down, no credentials needed on the target side.

Push-based (StatsD, Graphite): Applications push metrics to a central collector. Better for short-lived jobs (like batch scripts) that may end before Prometheus scrapes them. Use Prometheus Pushgateway for these use cases.