Checkmk Plugins

A collection of open-source extensions for Checkmk – agent-based checks, local checks, special agents, rulesets and graphing definitions – built for real-world homelab and small-business monitoring.

Plugins

Plugin	Type	Description	Checkmk	Latest release
windows_update_tracker	Agent plugin + checks + bakery	Pending Windows updates with per-update age rules, pending reboot, failed installations, Defender filter	2.4, 2.5	–

Each plugin lives in its own directory under plugins/ with a dedicated README and changelog.

Compatibility

All plugins target the current plugin APIs (cmk.agent_based.v2, cmk.rulesets.v1, cmk.graphing.v1, cmk.server_side_calls.v1) and are tested on Checkmk 2.4 and/or Checkmk 2.5. The supported versions are listed per plugin. Legacy (pre-2.3) APIs are not supported.

Installation

Download the .mkp file of the desired plugin from the Releases page.

Via the GUI (commercial editions): Setup → Extension packages → Upload package, then enable it.

Via the command line (all editions, including Checkmk Community/Raw):

# as the site user
mkp add /path/to/<plugin>-<version>.mkp
mkp enable <plugin> <version>
cmk -R   # or: omd restart apache, depending on the plugin type

Some plugins additionally ship an agent plugin or local check that has to be deployed to the monitored host – see the plugin's README for details.

Repository layout

plugins/
└── <plugin-name>/
    ├── README.md
    ├── CHANGELOG.md
    └── local/                    # mirrors the layout of a Checkmk site ($OMD_ROOT/local)
        ├── lib/python3/cmk_addons/plugins/<plugin-name>/
        │   ├── agent_based/      # check plugins
        │   ├── rulesets/         # rule specs
        │   ├── graphing/         # metrics, graphs, perfometers
        │   └── server_side_calls/
        └── share/check_mk/agents/plugins/   # agent-side plugins (if any)

Because the directory structure matches $OMD_ROOT/local, a plugin can be copied (or symlinked) straight into a test site during development.

Releases & versioning

Plugins are versioned independently using Semantic Versioning. Releases are tagged as <plugin-name>-v<version> (e.g. nic-watchdog-v1.0.0) and the built .mkp package is attached to the corresponding GitHub Release.

Contributing

Issues and pull requests are welcome. Please run ruff check . and ruff format . before submitting.

License

This project is licensed under the GNU General Public License v2.0, the same license as Checkmk itself.

Copyright © 2026 Alexander Thomsen