Setting up Prometheus on Debian 9

14/10/2025

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A Step-by-Step Guide to Installing and Configuring Prometheus on Debian

In today’s complex IT environments, proactive monitoring is no longer a luxury—it’s a necessity. Understanding the performance and health of your servers is crucial for maintaining stability, troubleshooting issues, and ensuring a smooth user experience. Prometheus, a powerful open-source monitoring and alerting toolkit originally built at SoundCloud, has become an industry standard for collecting and analyzing time-series data.

This comprehensive guide will walk you through the entire process of installing and configuring Prometheus on a Debian server. We will cover everything from creating a dedicated user to setting up a systemd service for reliable operation.

Prerequisites

Before we begin, ensure you have the following:

A server running a recent version of Debian (such as 10, 11, or 12).
Access to a user account with sudo or root privileges.

Step 1: Create a Dedicated System User

For security purposes, it is a best practice to run services like Prometheus under their own dedicated, non-root user accounts. This isolates the service and limits its permissions on the system.

First, create a new system user and group named prometheus with no home directory or login shell.

sudo groupadd --system prometheus
sudo useradd -s /sbin/nologin --system -g prometheus prometheus

Next, we’ll create the necessary directories for Prometheus to store its configuration and data.

sudo mkdir /etc/prometheus
sudo mkdir /var/lib/prometheus

Finally, set the ownership of these directories to the prometheus user and group.

sudo chown prometheus:prometheus /etc/prometheus
sudo chown prometheus:prometheus /var/lib/prometheus

Step 2: Download and Install Prometheus

Prometheus is distributed as a pre-compiled binary, which simplifies the installation process.

Download the Latest Version:
Navigate to the official Prometheus downloads page to find the latest stable version for the linux-amd64 architecture. Copy the link address for the tarball.
Download and Extract the Archive:
Use wget to download the file to your home directory. Replace the URL below with the link you copied.
```
wget https://github.com/prometheus/prometheus/releases/download/v2.53.0/prometheus-2.53.0.linux-amd64.tar.gz
```
Once the download is complete, extract the contents of the archive.
```
tar xvf prometheus-2.53.0.linux-amd64.tar.gz
```
Install the Binaries:
Change into the newly created directory. You will find two main binary files: prometheus and promtool.
```
cd prometheus-2.53.0.linux-amd64/
```
Move these binaries to /usr/local/bin, a standard location for user-installed executables.
```
sudo mv prometheus /usr/local/bin/
sudo mv promtool /usr/local/bin/
```
Set the ownership of the binaries to the prometheus user.
```
sudo chown prometheus:prometheus /usr/local/bin/prometheus
sudo chown prometheus:prometheus /usr/local/bin/promtool
```
Install Configuration Files:
Move the consoles and console_libraries directories, along with the main configuration file prometheus.yml, to the /etc/prometheus directory we created earlier.
```
sudo mv consoles /etc/prometheus
sudo mv console_libraries /etc/prometheus
sudo mv prometheus.yml /etc/prometheus/prometheus.yml
```
Ensure the ownership is correctly set for all files in /etc/prometheus.
```
sudo chown -R prometheus:prometheus /etc/prometheus
```

Step 3: Configure Prometheus

The core of Prometheus’s behavior is defined in its configuration file, prometheus.yml. By default, it is configured to monitor itself, which is a great way to verify that the installation is working correctly.

Let’s review the default configuration file. You can open it with a text editor like nano:

sudo nano /etc/prometheus/prometheus.yml

The file will look something like this:

global:
  scrape_interval: 15s

scrape_configs:
  - job_name: 'prometheus'
    static_configs:
      - targets: ['localhost:9090']

This configuration tells Prometheus to:

scrape_interval: 15s: Collect metrics from its targets every 15 seconds.
job_name: 'prometheus': Define a job named “prometheus”.
targets: ['localhost:9090']: The target for this job is Prometheus itself, which exposes its own metrics on port 9090.

No changes are needed for now. We can expand this file later to add more monitoring targets.

Step 4: Create a systemd Service File

To manage Prometheus as a standard system service (allowing it to start on boot and be managed with systemctl), we need to create a systemd unit file.

Create a new file at /etc/systemd/system/prometheus.service:

sudo nano /etc/systemd/system/prometheus.service

Paste the following content into the file. This unit file specifies the user to run as and points to the correct configuration and data directories.

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

[Service]
User=prometheus
Group=prometheus
Type=simple
ExecStart=/usr/local/bin/prometheus \
    --config.file /etc/prometheus/prometheus.yml \
    --storage.tsdb.path /var/lib/prometheus/ \
    --web.console.templates=/etc/prometheus/consoles \
    --web.console.libraries=/etc/prometheus/console_libraries

[Install]
WantedBy=multi-user.target

Save and close the file. Now, reload the systemd daemon to make it aware of the new service.

sudo systemctl daemon-reload

Step 5: Start Prometheus and Verify Operation

With all the pieces in place, it’s time to start the service.

Start and Enable the Service:
Start the Prometheus service and enable it to launch automatically at system startup.
```
sudo systemctl start prometheus
sudo systemctl enable prometheus
```
Check the Status:
Verify that the service is running correctly.
```
sudo systemctl status prometheus
```
You should see an output indicating that the service is active (running).
Configure Firewall (If Necessary):
If you are using a firewall like ufw, you must allow traffic on port 9090.
```
sudo ufw allow 9090/tcp
```
Access the Web UI:
Open your web browser and navigate to your server’s IP address on port 9090:
http://YOUR_SERVER_IP:9090
You should now see the Prometheus web interface. To confirm it is scraping its own metrics, navigate to Status > Targets. You should see the prometheus job with a state of UP.

Conclusion and Next Steps

Congratulations! You have successfully installed and configured a fully operational Prometheus server on Debian. This setup provides a solid foundation for a robust monitoring system.

From here, your next steps could include:

Installing Node Exporter: Set up the Prometheus Node Exporter on your servers to collect detailed system-level metrics like CPU, memory, and disk usage.
Configuring Alertmanager: Set up Alertmanager to handle alerts and notify you via email, Slack, or other channels when metrics cross critical thresholds.
Visualizing with Grafana: Connect Grafana to your Prometheus instance to create beautiful, powerful, and interactive dashboards for visualizing your metrics.

By investing in a proper monitoring solution, you gain invaluable insights into your infrastructure, enabling you to build more reliable and performant systems.

Source: https://kifarunix.com/install-and-configure-prometheus-on-debian-9/