Learn how to install Prometheus on CentOS 8 with this comprehensive guide. Follow our step-by-step instructions to set up and configure Prometheus for monitoring your system’s performance and metrics. #centlinux #linux #prometheus
Table of Contents
What is Prometheus?
Prometheus is an open-source systems monitoring and alerting toolkit originally developed by SoundCloud. It has since become a standalone open-source project and is maintained by the Cloud Native Computing Foundation (CNCF). Prometheus is designed for reliability and scalability, making it a popular choice for monitoring complex and dynamic environments, especially those that rely on microservices architecture.
The project is written in Go and licensed under the Apache 2 License, with source code available on GitHub, and is a graduated project of the Cloud Native Computing Foundation, along with Kubernetes and Envoy.
Key features of Prometheus include:
- Multi-dimensional Data Model: Prometheus stores all data as time series, identified by metric names and key/value pairs called labels. This model allows for flexible and powerful queries.
- Powerful Query Language (PromQL): Prometheus provides PromQL, a functional query language that allows users to select and aggregate time series data in real-time.
- Pull-Based Model: Prometheus scrapes metrics from instrumented targets, which allows it to collect data at regular intervals. This pull-based approach makes it easy to integrate with various services and systems.
- Service Discovery: Prometheus supports service discovery mechanisms to automatically find targets to scrape, including static configuration, DNS, and integrations with various orchestration systems like Kubernetes.
- Alerting: Prometheus has a built-in alerting mechanism with its Alertmanager component. It allows users to define alert rules based on Prometheus query results and send notifications via various channels like email, Slack, or custom webhooks.
- Visualization: Prometheus can generate basic visualizations of data. Additionally, it integrates well with Grafana, a popular open-source visualization tool, for creating more sophisticated dashboards.
- Self-Contained: Prometheus is designed to run standalone without external dependencies, making it easy to deploy and manage.
Prometheus is widely used for monitoring cloud-native applications, infrastructure, and more due to its robustness, flexibility, and scalability.
How to use Prometheus?
A typical monitoring platform with Prometheus is composed of multiple tools.
- Multiple exporters that typically run on the monitored host to export local metrics.
- Prometheus to centralize and store the metrics.
- Alertmanager to trigger alerts based on those metrics.
- Grafana to produce dashboards.
- PromQL is the query language used to create dashboards and alerts.
Prometheus Alternatives
There are several alternatives to Prometheus for monitoring and alerting in various environments. Each has its own strengths and weaknesses, catering to different use cases and preferences. Here are some popular Prometheus alternatives:
Grafana Loki
- Description: Loki is a log aggregation system designed to work seamlessly with Grafana. While it’s primarily for logs rather than metrics, it integrates well with Grafana for a comprehensive monitoring solution.
- Strengths: Tailored for logs, efficient storage, and querying of log data, integrates seamlessly with Grafana.
InfluxDB
- Description: A time-series database optimized for fast, high-availability storage and retrieval of time series data.
- Strengths: High performance, SQL-like query language (Flux), part of the TICK stack (Telegraf, InfluxDB, Chronograf, Kapacitor).
Graphite
- Description: A monitoring tool that stores numeric time-series data and renders graphs of this data on demand.
- Strengths: Simple design, well-established, good at handling large amounts of data, wide range of integrations.
Zabbix
- Description: An enterprise-level monitoring platform designed for monitoring and tracking the status of various network services, servers, and other network hardware.
- Strengths: Extensive out-of-the-box monitoring templates, robust alerting, strong SNMP support, good for infrastructure monitoring.
Nagios
- Description: One of the oldest and most established monitoring systems, primarily used for monitoring hosts, services, and network hardware.
- Strengths: Flexible, strong community support, numerous plugins and integrations, reliable alerting.
Datadog
- Description: A cloud-based monitoring and analytics platform for infrastructure, application performance, and log management.
- Strengths: Comprehensive monitoring capabilities, user-friendly interface, seamless integration with various cloud providers, powerful dashboarding and visualization tools.
Sensu
- Description: A monitoring system designed for monitoring servers, services, and application health across complex infrastructure.
- Strengths: Scalable, API-driven, strong support for event processing and custom checks, good for dynamic environments.
Sysdig
- Description: A monitoring and security platform designed for cloud-native environments, with deep visibility into containerized applications.
- Strengths: Strong container and Kubernetes support, detailed system call visibility, security features integrated with monitoring.
Elastic Stack (ELK)
- Description: Comprises Elasticsearch, Logstash, and Kibana, used for searching, analyzing, and visualizing log data in real-time.
- Strengths: Powerful full-text search, robust visualization capabilities with Kibana, wide range of data source integrations.
Each of these alternatives has its unique features and is suited for different monitoring requirements. The choice of tool depends on factors such as the complexity of the environment, specific monitoring needs, integration capabilities, and personal or organizational preferences.
Recommended Training: Prometheus | The Complete Hands-On for Monitoring & Alerting from Sean Bradley
Environment Specification
We are using a minimal RHEL 8 virtual machine with following specifications.
- CPU – 3.4 Ghz (2 cores)
- Memory – 2 GB
- Storage – 20 GB
- Operating System – Red Hat Enterprise Linux 8.4
- Hostname – prometheus-01.centlinux.com
- IP Address – 192.168.116.238 /24
Update your Linux Operating System
Connect with prometheus-01.centlinux.com as root user by using a ssh client.
Update your Linux operating system by using dnf command.
# dnf update -y
If the above command updates your Linux Kernel, then reboot your Linux operating system with new Kernel.
# reboot
Verify the Linux operating system and Kernel versions, that are being used in this article.
# cat /etc/redhat-release Red Hat Enterprise Linux release 8.4 (Ootpa) # uname -r 4.18.0-305.12.1.el8_4.x86_64
Switch SELinux Target Policy to Permissive Mode
Prometheus currently does not includes an official SELinux policy. Therefore, your have to disable SELinux or switch it into permissive mode for proper functioning of your network monitoring software.
You can execute following commands at Linux Bash prompt to switch SELinux target policy to permissive mode.
# sed -i 's/^SELINUX=.*/SELINUX=permissive/g' /etc/sysconfig/selinux # setenforce permissive
Create Prometheus User and Directories
Create a Linux user to own Prometheus software and processes.
# useradd --no-create-home -s /bin/false prometheus
Create required Prometheus directories and adjust the ownership.
# mkdir /etc/prometheus # mkdir /var/lib/prometheus # chown prometheus:prometheus /etc/prometheus # chown prometheus:prometheus /var/lib/prometheus
Install Prometheus on CentOS 8
You can free download systems monitoring tool from Prometheus official website.
You can use wget command to download Prometheus tarball directly from the Linux CLI. If you don’t have wget command, then install Prometheus on CentOS 8 by using dnf command.
# wget https://github.com/prometheus/prometheus/releases/download/v2.29.2/prometheus-2.29.2.linux-amd64.tar.gz -P /tmp --2021-09-05 14:30:50-- https://github.com/prometheus/prometheus/releases/download/v2.29.2/prometheus-2.29.2.linux-amd64.tar.gz ... Connecting to github-releases.githubusercontent.com (github-releases.githubusercontent.com)|185.199.111.154|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 73175122 (70M) [application/octet-stream] Saving to: ‘/tmp/prometheus-2.29.2.linux-amd64.tar.gz’ prometheus-2.29.2.l 100%[===================>] 69.79M 300KB/s in 5m 21s 2021-09-05 14:36:13 (222 KB/s) - ‘/tmp/prometheus-2.29.2.linux-amd64.tar.gz’ saved [73175122/73175122]
Extract the downloaded tarball into the /var/lib/prometheus directory.
# tar -xf /tmp/prometheus-2.29.2.linux-amd64.tar.gz -C /var/lib/prometheus/ --strip-components=1
Adjust the ownership of the extracted files.
# chown -R prometheus:prometheus /var/lib/prometheus
Move Prometheus configuration file to /etc/prometheus directory.
# mv /var/lib/prometheus/prometheus.yml /etc/prometheus/
Check the default configurations in prometheus.yml file.
# grep -v '#' /etc/prometheus/prometheus.yml
global:
alerting:
alertmanagers:
- static_configs:
- targets:
rule_files:
scrape_configs:
- job_name: "prometheus"
static_configs:
- targets: ["localhost:9090"]
Create symbolic links for Prometheus commands at /usr/bin directory to make them globally executable from any path.
# cp -s /var/lib/prometheus/prometheus /usr/bin # cp -s /var/lib/prometheus/promtool /usr/bin
Create Systemd Service Unit for Prometheus
To enable autostart of Prometheus server, you are required to create systemd service unit.
# vi /usr/lib/systemd/system/prometheus.service
Add following directives in this file.
[Unit] Description=Prometheus Wants=network-online.target After=network-online.target [Service] User=prometheus Group=prometheus Type=simple ExecStart=/usr/bin/prometheus --config.file /etc/prometheus/prometheus.yml --storage.tsdb.path /var/lib/prometheus/ --web.console.templates=/var/lib/prometheus/consoles --web.console.libraries=/var/lib/prometheus/console_libraries [Install] WantedBy=multi-user.target
Enable and start Prometheus service.
# systemctl enable --now prometheus.service Created symlink /etc/systemd/system/multi-user.target.wants/prometheus.service → /usr/lib/systemd/system/prometheus.service.
Configure Linux Firewall
This network monitoring server uses default port 9090/tcp. Therefore, it is necessary to allow it Linux firewall to make it accessible accross the network.
# firewall-cmd --permanent --add-port=9090/tcp
success
# firewall-cmd --reload
success
Access Prometheus GUI
Open URL http://prometheus-01.centlinux.com in a web browser.
Open Status > Targets from top menu.
Install Node Exporter on CentOS 8
Node Exporter is a Prometheus exporter for server level and level metrics with configurable metric collectors. It helps us in measuring various server resources such as RAM, disk space, and CPU utilization.
You need to install node_exporter on your Prometheus server to gather metrics.
Create directory for Node Exporter software.
# mkdir -p /var/lib/prometheus/node_exporter
Download Node Exporter tarball from Prometheus website.
# wget https://github.com/prometheus/node_exporter/releases/download/v1.2.2/node_exporter-1.2.2.linux-amd64.tar.gz -P /tmp --2021-09-05 15:09:51-- https://github.com/prometheus/node_exporter/releases/download/v1.2.2/node_exporter-1.2.2.linux-amd64.tar.gz ... Connecting to github-releases.githubusercontent.com (github-releases.githubusercontent.com)|185.199.109.154|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 8898481 (8.5M) [application/octet-stream] Saving to: ‘/tmp/node_exporter-1.2.2.linux-amd64.tar.gz’ node_exporter-1.2.2.linux-amd6 100%[==================================================>] 8.49M 74.0KB/s in 2m 12s 2021-09-05 15:12:07 (65.7 KB/s) - ‘/tmp/node_exporter-1.2.2.linux-amd64.tar.gz’ saved [8898481/8898481]
Extract downloaded tarball into /var/lib/prometheus/node_exporter/ directory.
# tar xf /tmp/node_exporter-1.2.2.linux-amd64.tar.gz -C /var/lib/prometheus/node_exporter/ --strip-components=1
Adjust directory ownership.
# chown -R prometheus:prometheus /var/lib/prometheus/node_exporter/
Create a symbolic link for node_exporter at /usr/bin directory.
# cp -s /var/lib/prometheus/node_exporter/node_exporter /usr/bin/
Enable autostart of node_exporter process, create a systemd service unit.
# vi /usr/lib/systemd/system/node_exporter.service
Add following lines of code in this file.
[Unit] Description=Node Exporter Wants=network-online.target After=network-online.target [Service] User=prometheus ExecStart=/usr/bin/node_exporter [Install] WantedBy=default.target
Enable and start Node Exporter service.
# systemctl enable --now node_exporter.service Created symlink /etc/systemd/system/default.target.wants/node_exporter.service → /usr/lib/systemd/system/node_exporter.service.
Configure Linux firewall to allow node_exporter default port 9100/tcp.
# firewall-cmd --permanent --add-port=9100/tcp success # firewall-cmd --reload success
Edit Prometheus configuration file in vim text editor.
# vi /etc/prometheus/prometheus.yml
Add the node_exporter endpoint configuration in this file.
- job_name: 'node_exporter'
static_configs:
- targets: ['localhost:9100']
Restart Prometheus service to load new configurations.
# systemctl restart prometheus.service
Open Status > Targets or refresh the web page, if already opened.
Final Thoughts
In conclusion, installing Prometheus on CentOS 8 is a straightforward process that involves downloading the Prometheus binary, configuring the system for optimal performance, and ensuring that the service starts automatically upon boot. By following the necessary steps—such as adding the Prometheus user, configuring the system firewall, and setting up the service file—Prometheus can be successfully installed and ready for monitoring your systems and applications.
With Prometheus running on CentOS 8, you gain powerful metrics collection and monitoring capabilities, making it easier to track system performance, troubleshoot issues, and ensure the health of your infrastructure. Whether you’re using Prometheus for a small setup or scaling it for a larger environment, its flexibility and integration with other tools like Grafana make it a valuable addition to your monitoring stack.
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