Node Exporter

This is a service you install on your end-points to make CPU/Memory/Etc. metrics available to Prometheus.

Installation

On each device you want to monitor, install the node exporter with this command.

sudo apt install prometheus-node-exporter

Do a quick test to make sure it’s responding to scrapes.

curl localhost:9100/metrics

Configuration

Back on your Prometheus server, add these new nodes as a job in the prometheus.yaml file. Feel free to drop the initial job where Prometheus was scraping itself.

global:
  scrape_interval: 15s
scrape_configs:
  - job_name: 'servers'
    static_configs:
    - targets:
      - some.server:9100
      - some.other.server:9100
      - and.so.on:9100

sudo systemctl reload prometheus.service

Operation

You can check the status of your new targets at:

http://some.server:9090/classic/targets

A lot of data is provided by the node by default. This can have a noticeable impact on low-power systems. To reduce this, customize the node’s config to enable only specific collectors.

In the case below we reduce collection to just CPU, Memory, and Hardware metrics. When scraping a Pi 3B, this reduces the Scrape Duration from 500 to 50ms.

# Do this on the node you're monitoring
sudo sed -i 's/^ARGS.*/ARGS="--collector.disable-defaults --collector.hwmon --collector.cpu --collector.meminfo"/' /etc/default/prometheus-node-exporter
sudo systemctl restart prometheus-node-exporter

The available collectors are listed on the page:

https://github.com/prometheus/node_exporter