How to use Prometheus to Monitor Complex Applications and Infrastructure

This article explains Prometheus, an open-source monitoring system for microservices and monolithic applications, detailing its architecture (retrieval, time-series database, HTTP server), core metric types (Counter, Gauge, Histogram, Summary), and practical Python examples for exposing metrics. It further walks through Prometheus configuration via YAML, running the service (binary and Docker), accessing the UI for queries, and defining alerting rules with Alertmanager to route notifications.