# Prometheus Node Exporter — Hardware and OS Metrics for Unix Systems

> Node Exporter is the official Prometheus exporter for machine-level metrics, exposing CPU, memory, disk, filesystem, and network statistics from Linux and other Unix systems via an HTTP endpoint.

## Install

Save in your project root:

# Prometheus Node Exporter — Hardware and OS Metrics for Unix Systems

## Quick Use
```bash
# Download and run
wget https://github.com/prometheus/node_exporter/releases/download/v1.8.2/node_exporter-1.8.2.linux-amd64.tar.gz
tar xvfz node_exporter-*.tar.gz
cd node_exporter-* && ./node_exporter

# Scrape metrics
curl http://localhost:9100/metrics

# Add to prometheus.yml
# scrape_configs:
#   - job_name: node
#     static_configs:
#       - targets: ['localhost:9100']
```

## Introduction
Node Exporter is the standard way to feed host-level metrics into Prometheus. It reads data from Linux pseudo-filesystems (`/proc`, `/sys`) and exposes hundreds of hardware and kernel metrics on a single HTTP endpoint that Prometheus scrapes.

## What Node Exporter Does
- Exposes CPU usage per core and per mode (user, system, idle, iowait)
- Reports memory, swap, and hugepage statistics from /proc/meminfo
- Tracks disk I/O, filesystem space, and mount-point health
- Monitors network interface bytes, packets, errors, and drops
- Provides thermal, power supply, and hardware sensor readings via sysfs

## Architecture Overview
Node Exporter is a single Go binary that registers a set of collectors. Each collector reads from a specific Linux subsystem (procfs, sysfs, ethtool, etc.) and emits Prometheus-format metrics. Collectors are enabled or disabled via CLI flags. The binary listens on port 9100 and responds to GET /metrics with a text exposition of all enabled collectors.

## Self-Hosting & Configuration
- Run as a systemd service with `--web.listen-address=:9100`
- Disable unneeded collectors with `--no-collector.<name>` flags
- Enable optional collectors like `systemd`, `processes`, or `tcpstat` explicitly
- Use `--collector.textfile.directory` to expose custom metrics from cron jobs
- Deploy as a Kubernetes DaemonSet using the Prometheus community Helm chart

## Key Features
- 40+ built-in collectors covering CPU, memory, disk, network, and more
- Textfile collector: drop `.prom` files to expose custom batch metrics
- TLS and basic auth support for secure metric endpoints
- Low overhead: typically under 15 MB RSS and negligible CPU
- Pairs with Grafana's Node Exporter Full dashboard for instant visibility

## Comparison with Similar Tools
- **Telegraf** — push-based, multi-output; Node Exporter is Prometheus-native pull
- **cAdvisor** — container-level metrics; Node Exporter covers the host OS
- **collectd** — plugin-based collector; Node Exporter is simpler, single-purpose
- **Netdata** — real-time dashboard included; Node Exporter is headless, pairs with Grafana

## FAQ
**Q: Does Node Exporter work on macOS or Windows?**
A: macOS is partially supported. Windows has a separate project: windows_exporter.

**Q: How do I add custom metrics?**
A: Write a script that outputs Prometheus text format to a `.prom` file in the textfile directory. Node Exporter serves them automatically.

**Q: What is the scrape performance impact?**
A: A typical scrape takes 50-200 ms and produces 1-3 MB of text. Impact on the host is negligible.

**Q: Can I filter which metrics Prometheus collects?**
A: Yes. Use `metric_relabel_configs` in Prometheus or `--collector.disable-defaults` with explicit `--collector.<name>` flags.

## Sources
- https://github.com/prometheus/node_exporter
- https://prometheus.io/docs/guides/node-exporter/

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Source: https://tokrepo.com/en/workflows/ea6dae1a-3f30-11f1-9bc6-00163e2b0d79
Author: AI Open Source