What is Prometheus in Kubernetes?

Prometheus is an open-source application used for metrics-based monitoring and alerting. Prometheus calls out to your application, pulls real-time metrics, compresses and stores them in a time-series database. Moreover, it offers a powerful data model and a query language and can provide detailed and actionable metrics. When you deploy a new version of the app, k8s creates a new pod (container) and after the pod is ready k8s destroy the old one. It is on a constant vigil, watching the k8s API and when detects a change it creates a new Prometheus configuration, based on the services (pods) changes.