kubernetes-the-hard-way/docs/06-kubernetes-worker.md

# Bootstrapping Kubernetes Workers

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

* worker0
* worker1
* worker2

## 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 machine 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`, `worker1`, `worker2`:

### 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')
```

---

```
sudo mkdir -p /var/lib/kubelet
```

```
sudo mv bootstrap.kubeconfig kube-proxy.kubeconfig /var/lib/kubelet
```

#### Move the TLS certificates in place

```
sudo mkdir -p /var/lib/kubernetes
```

```
sudo mv ca.pem /var/lib/kubernetes/
```

#### Docker

```
wget https://get.docker.com/builds/Linux/x86_64/docker-1.12.6.tgz
```

```
tar -xvf docker-1.12.6.tgz
```

```
sudo cp docker/docker* /usr/bin/
```

Create the Docker systemd unit file:


```
cat > docker.service <<EOF
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.io

[Service]
ExecStart=/usr/bin/docker daemon \\
  --iptables=false \\
  --ip-masq=false \\
  --host=unix:///var/run/docker.sock \\
  --log-level=error \\
  --storage-driver=overlay
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF
```

Start the docker service:

```
sudo mv docker.service /etc/systemd/system/docker.service
```

```
sudo systemctl daemon-reload
sudo systemctl enable docker
sudo systemctl start docker
```

```
sudo docker version
```


#### kubelet

The Kubernetes kubelet no longer relies on docker networking for pods! The Kubelet can now use [CNI - the Container Network Interface](https://github.com/containernetworking/cni) to manage machine level networking requirements.

Download and install CNI plugins

```
sudo mkdir -p /opt/cni
```

```
wget https://storage.googleapis.com/kubernetes-release/network-plugins/cni-amd64-0799f5732f2a11b329d9e3d51b9c8f2e3759f2ff.tar.gz
```

```
sudo tar -xvf cni-amd64-0799f5732f2a11b329d9e3d51b9c8f2e3759f2ff.tar.gz -C /opt/cni
```


Download and install the Kubernetes worker binaries:

```
wget https://storage.googleapis.com/kubernetes-release/release/v1.6.0-beta.4/bin/linux/amd64/kubectl
```
```
wget https://storage.googleapis.com/kubernetes-release/release/v1.6.0-beta.4/bin/linux/amd64/kube-proxy
```
```
wget https://storage.googleapis.com/kubernetes-release/release/v1.6.0-beta.4/bin/linux/amd64/kubelet
```

```
chmod +x kubectl kube-proxy kubelet
```

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

Create the kubelet systemd unit file:

```
cat > kubelet.service <<EOF
[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/GoogleCloudPlatform/kubernetes
After=docker.service
Requires=docker.service

[Service]
ExecStart=/usr/bin/kubelet \\
  --api-servers=https://${KUBERNETES_PUBLIC_ADDRESS}:6443 \\
  --allow-privileged=true \\
  --cloud-provider=auto-detect \\
  --cluster-dns=10.32.0.10 \\
  --cluster-domain=cluster.local \\
  --container-runtime=docker \\
  --experimental-bootstrap-kubeconfig=/var/lib/kubelet/bootstrap.kubeconfig \\
  --network-plugin=kubenet \\
  --kubeconfig=/var/lib/kubelet/kubeconfig \\
  --serialize-image-pulls=false \\
  --register-node=true \\
  --tls-cert-file=/var/run/kubernetes/kubelet-client.crt \\
  --tls-private-key-file=/var/run/kubernetes/kubelet-client.key \\
  --v=2
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target
EOF
```

```
sudo mv kubelet.service /etc/systemd/system/kubelet.service
```

```
sudo chmod +w /var/run/kubernetes
```

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

```
sudo systemctl status kubelet --no-pager
```

#### kube-proxy


```
cat > kube-proxy.service <<EOF
[Unit]
Description=Kubernetes Kube Proxy
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

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

[Install]
WantedBy=multi-user.target
EOF
```

```
sudo mv kube-proxy.service /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`, `worker1`, and `worker2`

## Approve the TLS certificate requests

Each worker node will submit a certificate signing request which must be approved before the node is allowed to join the cluster.

Log into one of the controller nodes:

```
gcloud compute ssh controller0
```

List the pending certificate requests:

```
kubectl get csr
```

> Use the kubectl describe csr command to view the details of a specific signing request.

Approve each certificate signing request using the `kubectl certificate approve` command:

```
kubectl certificate approve <csr-name>
```

Once all certificate signing requests have been approved all nodes should be registered with the cluster:

```
kubectl get nodes
```

```
NAME      STATUS    AGE       VERSION
worker0   Ready     7m        v1.6.0-beta.4
worker1   Ready     5m        v1.6.0-beta.4
worker2   Ready     2m        v1.6.0-beta.4
```