Lab 8: Bootstrapping the Kubernetes Control Plane¶

This is a fork of the original "Kubernetes the hard way" originally written by Kelsey Hightower (GitHub: kelseyhightower). Unlike the original that bases itself on Debian like distributions for the ARM64 architecture, this fork targets Enterprise Linux distributions such as Rocky Linux running on x86_64 architecture.

In this lab you will bootstrap the Kubernetes control plane. You will install the following components on the controller machine: Kubernetes API Server, Scheduler, and Controller Manager.

Prerequisites¶

Connect to the jumpbox and copy Kubernetes binaries and systemd unit files to the server instance:

scp \
  downloads/kube-apiserver \
  downloads/kube-controller-manager \
  downloads/kube-scheduler \
  downloads/kubectl \
  units/kube-apiserver.service \
  units/kube-controller-manager.service \
  units/kube-scheduler.service \
  configs/kube-scheduler.yaml \
  configs/kube-apiserver-to-kubelet.yaml \
  root@server:~/

You must run the commands in the following sections of this lab on the server machine. Login to the controller instance with the ssh command. Example:

ssh root@server

Provision the Kubernetes Control Plane¶

Create the Kubernetes configuration directory:

mkdir -p /etc/kubernetes/config

Install the Kubernetes Controller Binaries¶

Install the Kubernetes binaries:

  chmod +x kube-apiserver \
    kube-controller-manager \
    kube-scheduler kubectl

  mv kube-apiserver \
    kube-controller-manager \
    kube-scheduler kubectl \
    /usr/local/bin/

Configure the Kubernetes API Server¶

  mkdir -p /var/lib/kubernetes/

  mv ca.crt ca.key \
    kube-api-server.key kube-api-server.crt \
    service-accounts.key service-accounts.crt \
    encryption-config.yaml \
    /var/lib/kubernetes/

Create the kube-apiserver.service systemd unit file:

mv kube-apiserver.service /etc/systemd/system/kube-apiserver.service

Configure the Kubernetes Controller Manager¶

Move the kube-controller-manager kubeconfig into place:

mv kube-controller-manager.kubeconfig /var/lib/kubernetes/

Create the kube-controller-manager.service systemd unit file:

mv kube-controller-manager.service /etc/systemd/system/

Configure the Kubernetes Scheduler¶

Move the kube-scheduler kubeconfig into place:

mv kube-scheduler.kubeconfig /var/lib/kubernetes/

Create the kube-scheduler.yaml configuration file:

mv kube-scheduler.yaml /etc/kubernetes/config/

Create the kube-scheduler.service systemd unit file:

mv kube-scheduler.service /etc/systemd/system/

Start the Controller Services¶

  systemctl daemon-reload

  systemctl enable kube-apiserver \
    kube-controller-manager kube-scheduler

  systemctl start kube-apiserver \
    kube-controller-manager kube-scheduler

Allow up to 10 seconds for the Kubernetes API Server to fully initialize.

Verification¶

kubectl cluster-info   --kubeconfig admin.kubeconfig

Kubernetes control plane is running at https://127.0.0.1:6443

RBAC for Kubelet Authorization¶

In this section you will configure RBAC permissions to allow the Kubernetes API Server to access the Kubelet API on each worker node. Access to the Kubelet API is required for retrieving metrics, logs, and executing commands in pods.

This tutorial sets the Kubelet --authorization-mode flag to Webhook. Webhook mode uses the SubjectAccessReview API to determine authorization.

Run the commands in this section on the controller node, which will affect the entire cluster.

ssh root@server

Create the system:kube-apiserver-to-kubelet ClusterRole with permissions to access the Kubelet API and perform most common tasks associated with managing pods:

kubectl apply -f kube-apiserver-to-kubelet.yaml \
  --kubeconfig admin.kubeconfig

RBAC Verification¶

At this point the Kubernetes control plane is up and running. Run the following commands from the jumpbox machine to verify it is working:

Make a HTTP request for the Kubernetes version info:

curl -k --cacert ca.crt https://server.kubernetes.local:6443/version

{
  "major": "1",
  "minor": "32",
  "gitVersion": "v1.32.0",
  "gitCommit": "70d3cc986aa8221cd1dfb1121852688902d3bf53",
  "gitTreeState": "clean",
  "buildDate": "2024-12-11T17:59:15Z",
  "goVersion": "go1.23.3",
  "compiler": "gc",
  "platform": "linux/amd64"
}

Next: Bootstrapping the Kubernetes Worker Nodes

Author: Wale Soyinka

Contributors: Steven Spencer