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Werk #19445: kube_node_count: Fix control-plane node detection with default role name

Component Checks & agents
Title kube_node_count: Fix control-plane node detection with default role name
Date Mar 20, 2026
Level Trivial Change
Class Bug Fix
Compatibility Incompatible - Manual interaction might be required
Checkmk versions & editions
2.6.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Ultimate MT
2.5.0b2
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Ultimate MT
2.4.0p26
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Ultimate MT

If you set up Kubernetes monitoring with default settings, your control plane nodes may have been incorrectly counted as worker nodes by the Nodes service (kube_node_count). This was caused by a typo in the default role name (control_plane instead of control-plane). Kubernetes has never used the underscore variant, so the default never matched anything.

The default role list now uses control-plane (hyphen), matching the standard Kubernetes naming convention. The master role (used by older clusters) remains in the defaults as well.

If your cluster uses non-standard node role names, you can configure them in the Kubernetes node count ruleset to ensure control plane nodes are counted correctly.

If you have customized this rule, please ensure that the role name you specify matches what your cluster actually uses to identify control-plane nodes. If you have not customized this rule, no action is needed to benefit from this fix.

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