05-kubernetes-configuration-files.md

Generating Kubernetes Configuration Files for Authentication

In this lab you will generate Kubernetes configuration files, also known as kubeconfigs, which enable Kubernetes clients to locate and authenticate to the Kubernetes API Servers.

Client Authentication Configs

In this section you will generate kubeconfig files for the controller manager, kubelet, kube-proxy, and scheduler clients and the admin user.

Kubernetes Public IP Address

This is on a home network, no load balancers. So, Kubernetes public address is the same as controller address:

KUBERNETES_PUBLIC_ADDRESS=`grep controller-1 /etc/hosts|cut -f 1 -d " "`

The kubelet Kubernetes Configuration File

When generating kubeconfig files for Kubelets the client certificate matching the Kubelet's node name must be used. This will ensure Kubelets are properly authorized by the Kubernetes Node Authorizer.

Generate a kubeconfig file for each worker node:

for instance in worker-1 worker-2 worker-3; do
  ./kubectl config set-cluster kubernetes-the-hard-way \
    --certificate-authority=ca.pem \
    --embed-certs=true \
    --server=https://${KUBERNETES_PUBLIC_ADDRESS}:6443 \
    --kubeconfig=${instance}.kubeconfig

  ./kubectl config set-credentials system:node:${instance} \
    --client-certificate=${instance}.pem \
    --client-key=${instance}-key.pem \
    --embed-certs=true \
    --kubeconfig=${instance}.kubeconfig

  ./kubectl config set-context default \
    --cluster=kubernetes-the-hard-way \
    --user=system:node:${instance} \
    --kubeconfig=${instance}.kubeconfig

  ./kubectl config use-context default --kubeconfig=${instance}.kubeconfig
done

Results:

worker-1.kubeconfig
worker-2.kubeconfig
worker-3.kubeconfig

The kube-controller-manager Kubernetes Configuration File

Generate a kubeconfig file for the kube-controller-manager service:

{
  ./kubectl config set-cluster kubernetes-the-hard-way \
    --certificate-authority=ca.pem \
    --embed-certs=true \
    --server=https://127.0.0.1:6443 \
    --kubeconfig=kube-controller-manager.kubeconfig

  ./kubectl config set-credentials system:kube-controller-manager \
    --client-certificate=kube-controller-manager.pem \
    --client-key=kube-controller-manager-key.pem \
    --embed-certs=true \
    --kubeconfig=kube-controller-manager.kubeconfig

  ./kubectl config set-context default \
    --cluster=kubernetes-the-hard-way \
    --user=system:kube-controller-manager \
    --kubeconfig=kube-controller-manager.kubeconfig

  ./kubectl config use-context default --kubeconfig=kube-controller-manager.kubeconfig
}

Results:

kube-controller-manager.kubeconfig

The kube-scheduler Kubernetes Configuration File

Generate a kubeconfig file for the kube-scheduler service:

{
  ./kubectl config set-cluster kubernetes-the-hard-way \
    --certificate-authority=ca.pem \
    --embed-certs=true \
    --server=https://127.0.0.1:6443 \
    --kubeconfig=kube-scheduler.kubeconfig

  ./kubectl config set-credentials system:kube-scheduler \
    --client-certificate=kube-scheduler.pem \
    --client-key=kube-scheduler-key.pem \
    --embed-certs=true \
    --kubeconfig=kube-scheduler.kubeconfig

  ./kubectl config set-context default \
    --cluster=kubernetes-the-hard-way \
    --user=system:kube-scheduler \
    --kubeconfig=kube-scheduler.kubeconfig

  ./kubectl config use-context default --kubeconfig=kube-scheduler.kubeconfig
}

Results:

kube-scheduler.kubeconfig

The admin Kubernetes Configuration File

Generate a kubeconfig file for the admin user:

{
  ./kubectl config set-cluster kubernetes-the-hard-way \
    --certificate-authority=ca.pem \
    --embed-certs=true \
    --server=https://127.0.0.1:6443 \
    --kubeconfig=admin.kubeconfig

  ./kubectl config set-credentials admin \
    --client-certificate=admin.pem \
    --client-key=admin-key.pem \
    --embed-certs=true \
    --kubeconfig=admin.kubeconfig

  ./kubectl config set-context default \
    --cluster=kubernetes-the-hard-way \
    --user=admin \
    --kubeconfig=admin.kubeconfig

  ./kubectl config use-context default --kubeconfig=admin.kubeconfig
}

Results:

admin.kubeconfig

Distribute the Kubernetes Configuration Files

Copy the appropriate kubelet and kube-proxy kubeconfig files to each worker instance:

for instance in worker-1 worker-2 worker-3; do
  scp ${instance}.kubeconfig  root@${instance}:/root
done

Copy the appropriate kube-controller-manager and kube-scheduler kubeconfig files to each controller instance:

for instance in controller-1 ; do
  scp admin.kubeconfig kube-controller-manager.kubeconfig kube-scheduler.kubeconfig root@${instance}:/root
done

Next: Generating the Data Encryption Config and Key