Munin Node (munin-node) is a background service (daemon) installed on individual servers or devices to collect system performance data. It functions as a lightweight data agent within the Munin Monitoring System, a free and open-source platform that tracks and graphs system metrics over time. How Munin Node Works
Munin utilizes a client-server architecture split into two main components:
Munin Master: The central server that periodically polls data, records it into Round Robin Databases (.rrd files), and generates HTML graph dashboards.
Munin Node: The client agent running on each monitored machine that listens for incoming polling requests from the master.
┌─────────────────┐ ┌────────────────┐ │ Munin Master │ ──(Port 4949)──>│ Munin Node │ │ (Data Grapher) │ <──(Raw Text)── │ (Metric Agent) │ └─────────────────┘ └────────────────┘ │ ▼ ┌──────────────┐ │ Plugin Scripts│ │ (CPU, RAM…)│ └──────────────┘
The node itself does not analyze or graph any metrics. Instead, it waits for the master to connect on TCP port 4949 (usually every 5 minutes). When a request is received, the node executes small scripts called plugins, captures their text output, and transmits the data back to the master using a basic, line-based text protocol. Core Architecture and Features munin-node
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