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Installing Node exporter

The Prometheus Node Exporter exposes a wide variety of hardware- and kernel-related metrics. This has to be installed on every host you wish to monitor, a lot of tutorials mainly put it on a Docker host, which only monitors the Docker host node.

What if you want to monitor all your servers in your homelab. Here we will install node_exporter and start it as a service in Ubuntu.

Installing and running the Node Exporter

The Prometheus Node Exporter is a single static binary that you can install via tarball. Once you've downloaded it from the Prometheus downloads page extract it, and run it.

So if we were to go at to the downloads page at the time of writing this, the latest version is 1.7.0 and we want the linux-amd64 install. Therefore our below would be.

  • First download the file to your $HOME dir
  • Create a node_exporter directory within your /etc dir for safekeeping
  • cd into the new directory
  • Extract the node_exporter file
  • cd into the node_exporter directory
  • run ./node_exporter to get logs
# NOTE: Replace the URL with one from the above-mentioned "downloads" page.
# <VERSION>, <OS>, and <ARCH> are placeholders.
# wget https://github.com/prometheus/node_exporter/releases/download/v<VERSION>/node_exporter-<VERSION>.<OS>-<ARCH>.tar.gz

wget https://github.com/prometheus/node_exporter/releases/download/v1.7.0/node_exporter-1.7.0.linux-amd64.tar.gz

sudo mkdir /etc/node_exporter

cd /etc/node_exporter

tar xvfz $HOME/node_exporter-1.7.0.linux-amd64.tar.gz

cd node_exporter-1.7.0.linux-amd64

./node_exporter

Now this is mainly it, ...but every time we reboot the service won't start and we would need to start the node_exporter again. So let's create a service to start on boot.

Creating the service

I am installing this on my Proxmox node so we're doing this as root your command may differ, but you want to be placing your file within the systemd/system directory. Mine is lib/systemd/system/. Let's create the system file.

nano /lib/systemd/system/node_exporter.service

Add the following configuration

[Unit]
Description=Node Exporter
Documentation=https://prometheus.io/docs/guides/node-exporter/
Wants=network-online.target
After=network-online.target

[Service]
User=node_exporter
Group=node_exporter
Type=simple
Restart=on-failure
ExecStart=/etc/node_exporter/node_exporter-1.7.0.linux-amd64/node_exporter \
  --web.listen-address=:9100

[Install]
WantedBy=multi-user.target

Here is a breakdown of the above:

[Unit] Section

  • Description: Provides a brief description of the service. Here, "Node Exporter" indicates that this service is for running the Node Exporter.
  • Documentation: Points to the online documentation. This is useful for someone who needs more information about the service.
  • Wants: This line indicates that this service wants the network-online.target to be active, but it doesn't strictly require it. This means that the service prefers the network to be online but will start even if it's not.
  • After: Ensures that this service is started after the network-online.target. This is useful for making sure the network is available for the Node Exporter to function correctly.

[Service] Section

  • User and Group: Specify under which user and group the service will run. This is for security purposes, ensuring that the service has only the permissions it needs.
  • Type=simple: This is the simplest and most common service type. It tells systemd to consider the service up as soon as the process is running.
  • Restart=on-failure: Instructs systemd to restart the service if it fails (i.e., exits with a non-zero status code).
  • ExecStart: Specifies the command to start the service. Here, it's starting the Node Exporter binary (/etc/node_exporter/node_exporter-1.7.0.linux-amd64/node_exporter) and setting a flag to listen on port 9100 for web traffic (--web.listen-address=:9100).

[Install] Section

  • WantedBy=multi-user.target: This directive tells systemd to link this service file when the system is in a multi-user state (which is a common run level for fully operational, multi-user, networked systems). Essentially, it means that this service should be started by default in a regular, multi-user environment.

Once the file has been saved change the permissions on in chmod 664 /usr/lib/systemd/system/node_exporter.service

After changing the permissions you may need to create the node_exporter user and add it to the group so let us do that.

useradd -r -M -s /bin/false node_exporter
groupadd node_exporter
usermod -a -G node_exporter node_exporter

Reload systemd and Start Node Exporter

Now reload the systemd service to register the prometheus service and start the prometheus service.

systemctl daemon-reload
systemctl start node_exporter

Check the node exporter service status using the following command.

systemctl status node_exporter

root@pve2:~# systemctl status node_exporter
● node_exporter.service - Node Exporter
     Loaded: loaded (/lib/systemd/system/node_exporter.service; disabled; preset: enabled)
     Active: active (running) since Tue 2024-02-20 12:18:18 GMT; 6s ago
       Docs: https://prometheus.io/docs/guides/node-exporter/
   Main PID: 1031633 (node_exporter)
      Tasks: 5 (limit: 38268)
     Memory: 2.5M
        CPU: 7ms
     CGroup: /system.slice/node_exporter.service
             └─1031633 /etc/node_exporter/node_exporter-1.7.0.linux-amd64/node_exporter --web.listen-add>

Configure node_exporter to start at boot

systemctl enable node_exporter.service

Verify Node Exporter is Running

Verify the exporter is running by visiting the /metrics endpoint on the node on port 9100. You should be able to see something similar to the following:

# HELP go_gc_duration_seconds A summary of the pause duration of garbage collection cycles.
# TYPE go_gc_duration_seconds summary
go_gc_duration_seconds{quantile="0"} 0
go_gc_duration_seconds{quantile="0.25"} 0
go_gc_duration_seconds{quantile="0.5"} 0
go_gc_duration_seconds{quantile="0.75"} 0
go_gc_duration_seconds{quantile="1"} 0
go_gc_duration_seconds_sum 0
go_gc_duration_seconds_count 0
# HELP go_goroutines Number of goroutines that currently exist.
...

Clean up the install file

cd back to your $HOME directory or where you downloaded the .tar.gz file and run the following:

cd

rm -rf node_exporter-1.7.0.linux-amd64.tar.gz

Configuring your Prometheus instances

The Prometheus instance needs to be properly configured to access Node Exporter metrics. The following prometheus.yml example configuration file will tell the Prometheus instance to scrape, and how frequently, from the Node Exporter via localhost:9100:

global:
  scrape_interval: 15s

scrape_configs:
  - job_name: node
    static_configs:
      - targets: ['localhost:9100'] # IP of the node you installed node_exporter on.