CIS-1.3.6 - Ensure that the Controller Manager RotateKubeletServerCertificate argument is set to true

Ensure that the Controller Manager RotateKubeletServerCertificate argument is set to true

Framework

CIS

Severity

Medium

Description of the the issue

RotateKubeletServerCertificate causes the kubelet to both request a serving certificate after bootstrapping its client credentials and rotate the certificate as its existing credentials expire. This automated periodic rotation ensures that the there are no downtimes due to expired certificates and thus addressing availability in the CIA security triad.

Note: This recommendation only applies if you let kubelets get their certificates from the API server. In case your kubelet certificates come from an outside authority/tool (e.g. Vault) then you need to take care of rotation yourself.

Related resources

Pod

What does this control test

Enable kubelet server certificate rotation on controller-manager.

How to check it manually

Run the following command on the Control Plane node:

ps -ef | grep kube-controller-manager

Verify that RotateKubeletServerCertificate argument exists and is set to true.

Remediation

Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the Control Plane node and set the --feature-gates parameter to include RotateKubeletServerCertificate=true.

--feature-gates=RotateKubeletServerCertificate=true

Impact Statement

None

Default Value

By default, RotateKubeletServerCertificate is set to "true" this recommendation verifies that it has not been disabled.

Example

No example