Set Kubelet Parameters Via A Configuration File For RKE/RKE2/K3s Clusters

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Environment

RKE, RKE2, K3s

Situation

A subset of the kubelet's configuration parameters may be set via an on-disk config file, as a substitute for command-line flags. Providing parameters via a config file is the recommended approach because it simplifies node deployment and configuration management. The examples below cover adding the shutdownGracePeriod and the shutdownGracePeriodCriticalPods via the kubelet configuration file to RKE/RKE2/K3s clusters.

Resolution

Create the Kubelet configuration file with the parameters on all the nodes of the cluster. For example, create the file at /etc/kubernetes/kubeletconfig.yml

apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
shutdownGracePeriod: 30s
shutdownGracePeriodCriticalPods: 10s

RKE Clusters
For RKE, in the cluster.yml file, add the extra_bind to mount the file in the Kubelet and then provide the path to the configuration file as an extra_arg like the snippet below.

services:
  kubelet:
    extra_args: 
      config: /etc/kubernetes/kubeletconfig.yml
    extra_binds:
      - "/etc/kubernetes/kubeletconfig.yml:/etc/kubernetes/kubeletconfig.yml"

Run rke up for the configuration to be applied to the cluster.

RKE2/K3s Clusters
Add the configuration parameter under the Kubelet args in the config file located at /etc/rancher/{rke2|k3s}/config.yaml

kubelet-arg:
  - "--config=/etc/kubernetes/kubeletconfig.yml"

Restart the rke2/k3s service for the configuration to be applied.

NOTE
The Kubelet configuration file needs to be created on all the nodes of the cluster.

Additional Information

https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/
https://kubernetes.io/docs/reference/config-api/kubelet-config.v1beta1/

Disclaimer

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