03-auth-configs.md

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/v1.7.2/bin/darwin/amd64/kubectl
chmod +x kubectl
sudo mv kubectl /usr/local/bin

Linux

wget https://storage.googleapis.com/kubernetes-release/release/v1.7.2/bin/linux/amd64/kubectl
chmod +x kubectl
sudo mv kubectl /usr/local/bin

Windows

There are is no version of kubectl provided by the kubernetes projekt. A third party executable can be retrieved from a github project by Eirik Sletteberg. Instructions on how to build one local are provided as well.

Authentication

The following components will leverge Kubernetes RBAC:

• kubelet (client)
• kube-proxy (client)
• kubectl (client)

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.

Create the 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 to each controller node:

for host in icc-ctrl-1 icc-ctrl-2 icc-ctrl-3; do
  scp 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

KUBERNETES_PUBLIC_ADDRESS=$(dig -short YOUR_API_LOADBALANCER_SERVER_HOSTNAME | tail -1)

Create client kubeconfig files

Create the bootstrap kubeconfig file

kubectl config set-cluster informatik-compute-cloud \
  --certificate-authority=ca.pem \
  --embed-certs=true \
  --server=https://${KUBERNETES_PUBLIC_ADDRESS}:443 \
  --kubeconfig=bootstrap.kubeconfig

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

kubectl config set-context default \
  --cluster=YOUR_CLUSTER_NAME \
  --user=kubelet-bootstrap \
  --kubeconfig=bootstrap.kubeconfig

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

Create the kube-proxy kubeconfig

kubectl config set-cluster informatik-compute-cloud \
  --certificate-authority=ca.pem \
  --embed-certs=true \
  --server=https://${KUBERNETES_PUBLIC_ADDRESS}:443 \
  --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=YOUR_CLUSTER_NAME \
  --user=kube-proxy \
  --kubeconfig=kube-proxy.kubeconfig

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