Icinga

Icinga 2 is the monitoring engine at the center of the Icinga stack. It watches the availability of network resources and servers, raises notifications the moment something goes down, and emits performance data that downstream tools turn into graphs and reports. Its own configuration language describes what to check and when.

Configuration scales to large estates: write it as plain text in the Icinga DSL, manage it visually through Icinga Director, or generate it with config management tools. A REST API ships in the core, custom checks extend coverage to anything you can script, and the engine is built to run distributed across multiple sites.

Icinga 2 is licensed under GPLv3 or later, with some older source files under GPLv2 or later. It is self-hosted and pairs with Icinga Web 2 for the dashboard layer.