A Step-by-Step Guide to Installing Prometheus and Node Exporter on CentOS 7

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Prometheus is an open-source monitoring system that enables you to collect metrics from various configured target systems. It boasts a multi-dimensional data model, powerful queries, impressive visualization, and precise alerting. It’s highly versatile, thanks to numerous integrations.

Originally developed by SoundCloud in 2012, Prometheus has evolved into an independent open-source project maintained by the community. All components are available under the Apache 2 License on GitHub.

This tutorial will guide you through installing and configuring Prometheus alongside Node Exporter. We’ll set up Prometheus to monitor server metrics using CentOS 7.

Prerequisites

  • CentOS 7 server
  • Root privileges

Objectives

  1. Create a new user and download Prometheus
  2. Configure Prometheus as a Systemd service
  3. Configure Firewalld
  4. Install and configure Node Exporter
  5. Add Node Exporter to the Prometheus Server
  6. Perform testing

Step 1 – Create a New User and Download Prometheus

We’ll run the Prometheus service under a non-root user for enhanced security. Start by creating a new user named ‘prometheus’:

useradd -m -s /bin/bash prometheus

Log in as the new user and download Prometheus using wget:

su - prometheus
wget https://github.com/prometheus/prometheus/releases/download/v2.2.1/prometheus-2.2.1.linux-amd64.tar.gz

Extract and rename the downloaded file:

tar -xzvf prometheus-2.2.1.linux-amd64.tar.gz
mv prometheus-2.2.1.linux-amd64/ prometheus/

Your Prometheus files should reside in /home/prometheus/prometheus.

Step 2 – Configure Prometheus as a Systemd Service

Create a Systemd service to manage Prometheus easily. In the /etc/systemd/system directory, create a new service file:

cd /etc/systemd/system/
vim prometheus.service

Insert the following configuration:

  [Unit]
  Description=Prometheus Server
  Documentation=https://prometheus.io/docs/introduction/overview/
  After=network-online.target

  [Service]
  User=prometheus
  Restart=on-failure

  # Modify this line if Prometheus is downloaded elsewhere
  ExecStart=/home/prometheus/prometheus/prometheus \
    --config.file=/home/prometheus/prometheus/prometheus.yml \
    --storage.tsdb.path=/home/prometheus/prometheus/data

  [Install]
  WantedBy=multi-user.target

Save and exit the editor. Reload the Systemd configuration and enable Prometheus:

systemctl daemon-reload
systemctl start prometheus
systemctl enable prometheus

Configure Prometheus for systemd

Verify Prometheus is running:

systemctl status prometheus

Or use netstat to check the listening ports:

netstat -plntu

Check that prometheus is running

Ensure Prometheus is active on port 9090.

Step 3 – Configure Firewalld

If you’re using Firewalld, allow access through port 9090:

firewall-cmd --add-port=9090/tcp --permanent
firewall-cmd --reload

Access Prometheus’ interface by entering your server IP in a web browser:

http://192.168.33.10:9090/graph

Run a test query, like ‘http_requests_total,’ to visualize metrics:

Prometheus Graph

Step 4 – Install and Configure Node Exporter

Node Exporter collects machine metrics. Install it on the same server as Prometheus:

su - prometheus
wget https://github.com/prometheus/node_exporter/releases/download/v0.16.0-rc.1/node_exporter-0.16.0-rc.1.linux-amd64.tar.gz

Extract and rename the directory:

tar -xzvf node_exporter-0.16.0-rc.1.linux-amd64.tar.gz
mv node_exporter-0.16.0-rc.1.linux-amd64 node_exporter

Create a new Systemd service file for Node Exporter:

cd /etc/systemd/system/
vim node_exporter.service

Add the following configuration:

  [Unit]
  Description=Node Exporter
  Wants=network-online.target
  After=network-online.target

  [Service]
  User=prometheus
  ExecStart=/home/prometheus/node_exporter/node_exporter

  [Install]
  WantedBy=default.target

Save, exit, reload Systemd, and start Node Exporter:

systemctl daemon-reload
systemctl start node_exporter
systemctl enable node_exporter

Configure node_exporter systemd unit

Confirm Node Exporter is running, checking for activity on port 9100:

netstat -plntu

Check node_exporter port

Step 5 – Add Node Exporter to the Prometheus Server

Link Node Exporter to Prometheus by editing prometheus.yml:

su - prometheus
cd prometheus/
vim prometheus.yml

Add the following under scrape_config:

  - job_name: 'node_exporter'
    static_configs:
      - targets: ['localhost:9100']

Restart Prometheus to apply changes:

systemctl restart prometheus

Add node_exporter to the Prometheus Server

Step 6 – Testing Prometheus and Node Exporter

Open Prometheus in your browser:

http://192.168.33.10:9090/

To see memory metrics, enter:

node_memory_MemAvailable_bytes

This should display available server memory metrics collected by Node Exporter:

Result for node_memory_MemAvailable_bytes

To access Node Exporter raw data, ensure port 9100 is open:

firewall-cmd --add-port=9100/tcp
firewall-cmd --reload

Connect via:

http://192.168.33.10:9100/metrics

Result Metrics

This completes the installation and configuration of Prometheus and Node Exporter on CentOS 7.

References

FAQs

What is Prometheus?
Prometheus is an open-source monitoring and alerting toolkit, offering a robust solution for collecting and querying metrics from applications and systems.
Why use Node Exporter?
Node Exporter is ideal for collecting hardware and kernel metrics from your system, providing data that can be used by Prometheus for monitoring.
Can Prometheus monitor remote systems?
Yes, Prometheus can scrape metrics from remote systems where exporters are set up and configured.
Is Prometheus a replacement for traditional monitoring tools?
While highly effective, Prometheus is often used alongside other tools, providing complementary monitoring capabilities, especially within distributed environments.
Do I need root access to install Prometheus?
Root access simplifies the setup process, especially for system configurations and modifying firewall rules. However, Prometheus itself runs as a non-root user for security reasons.