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Setting up Authentication

In this lab you will setup the necessary authentication configs to enable Kubernetes clients to bootstrap and authenticate using RBAC (Role-Based Access Control).

Download and Install kubectl

The kubectl client will be used to generate kubeconfig files which will be consumed by the kubelet and kube-proxy services.

OS X

wget https://storage.googleapis.com/kubernetes-release/release/v1.6.0-beta.4/bin/darwin/amd64/kubectl
chmod +x kubectl
sudo mv kubectl /usr/local/bin

Linux

wget https://storage.googleapis.com/kubernetes-release/release/v1.6.0-beta.4/bin/linux/amd64/kubectl
chmod +x kubectl
sudo mv kubectl /usr/local/bin

Authentication

The following components will leverge Kubernetes RBAC:

kubelet (client)
Kubernetes API Server (server)

The other components, mainly the scheduler and controller manager, access the Kubernetes API server locally over the insecure API port which does not require authentication. The insecure port is only enabled for local access.

TLS Bootstrap Token

This section will walk you through the creation of a TLS bootstrap token that will be used to bootstrap TLS client certificates for kubelets.

Generate a token:

BOOTSTRAP_TOKEN=$(head -c 16 /dev/urandom | od -An -t x | tr -d ' ')

Generate a token file:

cat > token.csv <<EOF
${BOOTSTRAP_TOKEN},kubelet-bootstrap,10001,"system:kubelet-bootstrap"
EOF

Distribute the bootstrap token file

Copy the token.csv file to each controller node:

KUBERNETES_CONTROLLERS=(controller0 controller1 controller2)

for host in ${KUBERNETES_CONTROLLERS[*]}; do
  gcloud compute copy-files token.csv ${host}:~/
done

Client Authentication Configs

This section will walk you through creating kubeconfig files that will be used to bootstrap kubelets, which will then generate their own kubeconfigs based on dynamically generated certificates, and a kubeconfig for authenticating kube-proxy clients.

Each kubeconfig requires a Kubernetes master to connect to. To support H/A the IP address assigned to the load balancer sitting in front of the Kubernetes API servers will be used.

Set the Kubernetes Public Address

GCE

KUBERNETES_PUBLIC_ADDRESS=$(gcloud compute addresses describe kubernetes \
  --region us-central1 \
  --format 'value(address)')

AWS

KUBERNETES_PUBLIC_ADDRESS=$(aws elb describe-load-balancers \
  --load-balancer-name kubernetes | \
  jq -r '.LoadBalancerDescriptions[].DNSName')

Generate a bootstrap kubeconfig file:

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

kubectl config set-credentials kubelet-bootstrap \
  --token=${BOOTSTRAP_TOKEN} \
  --kubeconfig=bootstrap.kubeconfig

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

kubectl config use-context default --kubeconfig=bootstrap.kubeconfig

kube-proxy kubeconfig

Generate the kube-proxy kubeconfig file:

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

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

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

kubectl config use-context default --kubeconfig=kube-proxy.kubeconfig

Distribute client kubeconfig files

Copy the bootstrap and kube-proxy kubeconfig files to each worker node:

KUBERNETES_WORKER_NODES=(worker0 worker1 worker2)

GCE

for host in ${KUBERNETES_WORKER_NODES[*]}; do
  gcloud compute copy-files bootstrap.kubeconfig kube-proxy.kubeconfig ${host}:~/
done

AWS

for host in ${KUBERNETES_WORKER_NODES[*]}; do
  PUBLIC_IP_ADDRESS=$(aws ec2 describe-instances \
    --filters "Name=tag:Name,Values=${host}" | \
    jq -r '.Reservations[].Instances[].PublicIpAddress')
  scp -o "StrictHostKeyChecking no" bootstrap.kubeconfig kube-proxy.kubeconfig \
    ubuntu@${PUBLIC_IP_ADDRESS}:~/
done

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