Prometheus & Grafana, Explained

Prometheus scrapes and stores your metrics; Grafana queries and draws them. What each one actually does, how to read a PromQL query, and how to build dashboards and alerts that don't lie to you.

1. What Each One Does Prometheus is a time-series database that scrapes metrics from your services and stores them; Grafana is the dashboard layer that queries and visualizes them. Two tools, two jobs: collect-and-store vs display.
2. Metrics & a Taste of PromQL The three metric types (counter, gauge, histogram), what labels are for, and how to read a real PromQL query - including why you graph rate() over a counter instead of the raw number.
3. Dashboards & Alerting Build a panel that answers a real question, use RED/USE to decide what to chart, and fire an alert on a condition with Alertmanager - while avoiding dashboards nobody reads, alert fatigue, and cardinality blowups.