Prometheus

Figuring out what’s going on when something breaks can be difficult, so having the right tooling can make a big difference. Prometheus is one such tool. With proper tuning and configuration, it can even alert you before a failure occurs.

It also makes pretty graphs—everyone loves good visualisations!

Overview

Prometheus is a free and open‑source monitoring solution that collects and records metrics from servers, containers, and applications. It provides a flexible query language (PromQL) and powerful visualisation tools, and includes an alerting mechanism that sends notifications when needed.

Prerequisites

• A Centos derived Linux operating system
• Internet connectivity to download binaries
• sudo privileges
• wget installed

Steps

1. First we need to create a group and the prometheus user.

   sudo groupadd prometheus
   sudo useradd -m -s /usr/sbin/nologin -d /var/lib/prometheus --system -g prometheus prometheus
   

2. Create the configuration directory.

   sudo mkdir -p /etc/prometheus
   

3. Download the most recent (as of publication) of the prometheus LTS server. You can go to the downloads page to get a more recent version, or a version for a different hardware package.

   wget https://github.com/prometheus/prometheus/releases/download/v3.5.0/prometheus-3.5.0.linux-amd64.tar.gz
   tar xvzf prometheus*.tar.gz
   

4. Copy the executables and set permissions and owners.

   cd prometheus*/
   sudo mv prometheus /usr/local/bin
   sudo mv promtool /usr/local/bin
   sudo mv prometheus.yml /etc/prometheus
   sudo chown prometheus:prometheus /usr/local/bin/prometheus
   sudo chown prometheus:prometheus /usr/local/bin/promtool
   sudo chown -R prometheus:prometheus /etc/prometheus
   sudo chown -R prometheus:prometheus /var/lib/prometheus
   

5. If you are running SELinux you will need to execute the following to have systemd execute the file.

   sudo chcon -t bin_t /usr/local/bin/prometheus
   sudo semanage fcontext -a -t bin_t "/usr/local/bin/prometheus"
   sudo restorecon -v /usr/local/bin/prometheus
   

6. In order for prometheus to run at system start-up, you will need to create a systemd file. You can use the following as an example. If you wish to use other flags or command options, you can read the reference here.

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

   NOTE: This is an example systemd file for prometheus

   [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/
   
   [Install]
   WantedBy=multi-user.target
   

7. Enable and start the service.

   sudo systemctl daemon-reload
   sudo systemctl enable prometheus
   sudo systemctl start prometheus
   sudo systemctl status prometheus   
   

8. If you wish to configure prometheus, you can read about it here. The configuration file is located at /etc/prometheus.yml.

9. If you have the firewall enabled, you will need to open a port to view the UI.

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

Troubleshooting

Completion and Verification

• You should be able to:

  prometheus --version
  curl http://localhost:9090
  

Contacts

Appendix

References

• Flags
• Configuration

Changelog

• 2025/12/18 - Initial Version