After our introductory journey into the world of monitoring, it’s time to explore specific tools. Let’s start with one of the oldest yet still relevant solutions for those who value simplicity and clarity — Munin.

Munin is a lightweight and intuitive monitoring system specializing in collecting and graphically presenting system data. If you need a quick way to get a general view of your servers’ health without diving deep into complex configurations, Munin might be a great place to start.

What is Munin and How Does It Work?

Munin is based on a master-node architecture.

• Munin Master (Server) — the central component responsible for collecting data from all agents, storing it, and generating HTML reports with graphs.
• Munin Node (Agent) — installed on each monitored server or device. It provides data upon the server’s request using a set of plugins.

The working principle is simple: Munin Master periodically (usually every 5 minutes) connects to Munin Node, requests data via various plugins (e.g., for CPU, memory, disk, network activity). The received data is written into an RRDtool (Round Robin Database tool), optimized for time-series storage. Then Munin Master generates web pages with graphs, viewable in any browser.

Munin’s Strengths: Why Choose It?

Despite its age, Munin has several strong advantages:

• Simple installation and configuration: For basic monitoring, setting up Munin Master and Node takes just a few commands. Preconfigured plugins work almost out of the box.
• Wide range of ready-made plugins: A huge selection of predefined options for monitoring system parameters and popular services (Apache, Nginx, MySQL, PostgreSQL, etc.).
• HTML report generation: Static HTML pages with graphs — fast, simple, and doesn’t require a separate web interface.
• Low resource usage on agents: Munin Node is extremely lightweight and suitable even for low-end servers.
• Ease of writing custom plugins: Plugins are regular executable scripts (Bash, Python, Perl, etc.), making it easy to adapt Munin to specific needs.

Munin’s Weaknesses: What to Keep in Mind?

Where there are strengths, there are also limitations:

• Limited scalability: Munin is not designed to monitor hundreds or thousands of nodes. As infrastructure grows, performance issues may arise.
• Basic alerting system: Notification capabilities are limited. For advanced scenarios, you’ll need external mechanisms or switch to other tools.
• Static output: Graphs are PNG images. There’s no interactivity or data “drill-down” like in Grafana.
• Data storage (RRDtool): With long-term retention, data gets aggregated and loses granularity. Exact values from a year ago, for example, may no longer be available.

Usability and Unique Features

Munin is a perfect fit for:

• Small to medium infrastructures — from a few to a few dozen servers.
• Quick start — no training or lengthy configuration required.
• System administrators — who want to see the full picture on a single page.

Its unique strength is the ease of creating custom plugins and its high level of readiness out of the box.

Conclusion

Munin is a reliable “workhorse” for basic system monitoring. It doesn’t aim to be a universal solution for large-scale cloud infrastructures, but it handles visual oversight and basic diagnostics for small systems perfectly.

If you’re looking for a simple and clear tool, Munin is an excellent choice.

In the next article, we’ll explore a completely different approach to monitoring — one that has become the standard in modern cloud environments: Prometheus + Node Exporter + Grafana. Stay tuned!