Customizing components with the kubeadm API

All of these options are possible via the kubeadm configuration API. For more details on each field in the configuration you can navigate to our API reference pages.

Customizing the control plane with flags in ClusterConfiguration

The kubeadm ClusterConfiguration object exposes a way for users to override the default flags passed to control plane components such as the APIServer, ControllerManager, Scheduler and Etcd. The components are defined using the following structures:

• apiServer
• controllerManager
• scheduler
• etcd

These structures contain a common extraArgs field, that consists of key: value pairs. To override a flag for a control plane component:

1. Add the appropriate extraArgs to your configuration.
2. Add flags to the extraArgs field.
3. Run kubeadm init with --config <YOUR CONFIG YAML>.

APIServer flags

For details, see the reference documentation for kube-apiserver.

Example usage:

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: v1.16.0
apiServer:
  extraArgs:
    anonymous-auth: "false"
    enable-admission-plugins: AlwaysPullImages,DefaultStorageClass
    audit-log-path: /home/johndoe/audit.log

ControllerManager flags

For details, see the reference documentation for kube-controller-manager.

Example usage:

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: v1.16.0
controllerManager:
  extraArgs:
    cluster-signing-key-file: /home/johndoe/keys/ca.key
    deployment-controller-sync-period: "50"

Scheduler flags

For details, see the reference documentation for kube-scheduler.

Example usage:

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
kubernetesVersion: v1.16.0
scheduler:
  extraArgs:
    config: /etc/kubernetes/scheduler-config.yaml
  extraVolumes:
    - name: schedulerconfig
      hostPath: /home/johndoe/schedconfig.yaml
      mountPath: /etc/kubernetes/scheduler-config.yaml
      readOnly: true
      pathType: "File"

Etcd flags

For details, see the .

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
etcd:
  local:
    extraArgs:
      election-timeout: 1000

apiVersion: kubeadm.k8s.io/v1beta3
kind: InitConfiguration
patches:
  directory: /home/user/somedir

apiVersion: kubeadm.k8s.io/v1beta3
kind: JoinConfiguration
patches:
  directory: /home/user/somedir

• target can be one of kube-apiserver, kube-controller-manager, kube-scheduler and etcd.
• patchtype can be one of strategic, merge or json and these must match the patching formats supported by kubectl. The default patchtype is strategic.
• extension must be either json or yaml.
• suffix is an optional string that can be used to determine which patches are applied first alpha-numerically.

Customizing the kubelet

To customize the kubelet you can add a KubeletConfiguration next to the ClusterConfiguration or InitConfiguration separated by --- within the same configuration file. This file can then be passed to kubeadm init.

For more details see Configuring each kubelet in your cluster using kubeadm

Customizing kube-proxy

To customize kube-proxy you can pass a KubeProxyConfiguration next your ClusterConfiguration or InitConfiguration to kubeadm init separated by ---.

For more details you can navigate to our API reference pages.