Prometheus Fundamentals

Prometheus is an open-source monitoring and alerting toolkit originally built at SoundCloud and now a graduated project of the Cloud Native Computing Foundation (CNCF). It has become the de facto standard for metrics collection in cloud-native environments.

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A Brief History

• 2012 — Prometheus development begins at SoundCloud, inspired by Google's Borgmon
• 2015 — Prometheus is open-sourced
• 2016 — Prometheus joins the CNCF as the second hosted project (after Kubernetes)
• 2018 — Prometheus graduates from the CNCF
• Today — Prometheus is the most widely adopted open-source monitoring system

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Architecture Overview

Prometheus follows a pull-based architecture:

┌─────────────┐     scrape      ┌──────────────┐
│  Prometheus  │ ◄───────────── │  Application  │
│   Server     │     /metrics   │  (exporter)   │
└──────┬──────┘                 └──────────────┘
       │
       │  store
       ▼
┌─────────────┐     query      ┌──────────────┐
│   TSDB      │ ◄───────────── │   Grafana    │
│ (local disk)│    PromQL      │  Dashboard   │
└─────────────┘                └──────────────┘
       │
       │  evaluate
       ▼
┌─────────────┐     notify     ┌──────────────┐
│   Rules     │ ──────────────►│ Alertmanager │
│  (alerts)   │                └──────────────┘

Key Components