Set kubelet parameters via a configuration file for RKE, RKE2 and K3s clusters

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 shutdownGracePeriodCriticalPods parameters via the kubelet configuration file to RKE, RKE2 and K3s clusters.

Create the kubelet configuration file with the parameters on all the nodes of the cluster. For example, create the following 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 into the kubelet and then provide the path to the configuration file as an extra_arg, per 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.