# Bootstrapping the Kubernetes Worker Nodes

In this chapter, you will bootstrap three Kubernetes worker nodes. The following components will be installed on each node: [runc](https://github.com/opencontainers/runc), [gVisor](https://github.com/google/gvisor), [container networking plugins](https://github.com/containernetworking/cni), [containerd](https://github.com/containerd/containerd), [kubelet](https://kubernetes.io/docs/admin/kubelet), and [kube-proxy](https://kubernetes.io/docs/concepts/cluster-administration/proxies).


## Prerequisites

The commands in this chapter must be run on each worker node: `worker-1`, `worker-2`, and `worker-3`. Login to each worker node:

```
$ ssh -i ~/.ssh/id_rsa-k8s 10.240.0.21
```


### Running commands in parallel with tmux

[tmux](https://github.com/tmux/tmux/wiki) can be used to run commands on multiple virtual machines at the same time. See the [Running commands in parallel with tmux](01-prerequisites.md#running-commands-in-parallel-with-tmux) section in the Prerequisites lab.


## Provisioning a Kubernetes Worker Node

Install the OS dependencies:

```
$ {
  sudo apt-get update
  sudo apt-get -y install socat conntrack ipset
}
```

> The socat binary enables support for the `kubectl port-forward` command.

### Download and Install Worker Binaries

```
$ wget -q --show-progress --https-only --timestamping \
  https://github.com/kubernetes-sigs/cri-tools/releases/download/v1.12.0/crictl-v1.12.0-linux-amd64.tar.gz \
  https://storage.googleapis.com/kubernetes-the-hard-way/runsc-50c283b9f56bb7200938d9e207355f05f79f0d17 \
  https://github.com/opencontainers/runc/releases/download/v1.0.0-rc5/runc.amd64 \
  https://github.com/containernetworking/plugins/releases/download/v0.6.0/cni-plugins-amd64-v0.6.0.tgz \
  https://github.com/containerd/containerd/releases/download/v1.2.0-rc.0/containerd-1.2.0-rc.0.linux-amd64.tar.gz \
  https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kubectl \
  https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kube-proxy \
  https://storage.googleapis.com/kubernetes-release/release/v1.12.0/bin/linux/amd64/kubelet
```

Create the installation directories:

```
$ sudo mkdir -p \
  /etc/cni/net.d \
  /opt/cni/bin \
  /var/lib/kubelet \
  /var/lib/kube-proxy \
  /var/lib/kubernetes \
  /var/run/kubernetes
```

Install the worker binaries:

```
$ {
  sudo mv runsc-50c283b9f56bb7200938d9e207355f05f79f0d17 runsc
  sudo mv runc.amd64 runc
  chmod +x kubectl kube-proxy kubelet runc runsc
  sudo mv kubectl kube-proxy kubelet runc runsc /usr/local/bin/
  sudo tar -xvf crictl-v1.12.0-linux-amd64.tar.gz -C /usr/local/bin/
  sudo tar -xvf cni-plugins-amd64-v0.6.0.tgz -C /opt/cni/bin/
  sudo tar -xvf containerd-1.2.0-rc.0.linux-amd64.tar.gz -C /
}
```

### Configure CNI Networking

Get the Pod CIDR range for the current compute instance:

```
$ POD_CIDR=10.200.$(uname -n | awk -F"-" '{print $2}').0/24
```

Create the `bridge` network configuration file:

```
$ cat <<EOF | sudo tee /etc/cni/net.d/10-bridge.conf
{
    "cniVersion": "0.3.1",
    "name": "bridge",
    "type": "bridge",
    "bridge": "cnio0",
    "isGateway": true,
    "ipMasq": true,
    "ipam": {
        "type": "host-local",
        "ranges": [
          [{"subnet": "${POD_CIDR}"}]
        ],
        "routes": [{"dst": "0.0.0.0/0"}]
    }
}
EOF
```

Create the `loopback` network configuration file:

```
$ cat <<EOF | sudo tee /etc/cni/net.d/99-loopback.conf
{
    "cniVersion": "0.3.1",
    "type": "loopback"
}
EOF
```

### Configure containerd

Create the `containerd` configuration file:

```
$ sudo mkdir -p /etc/containerd/
```

```
$ cat << EOF | sudo tee /etc/containerd/config.toml
[plugins]
  [plugins.cri.containerd]
    snapshotter = "overlayfs"
    [plugins.cri.containerd.default_runtime]
      runtime_type = "io.containerd.runtime.v1.linux"
      runtime_engine = "/usr/local/bin/runc"
      runtime_root = ""
    [plugins.cri.containerd.untrusted_workload_runtime]
      runtime_type = "io.containerd.runtime.v1.linux"
      runtime_engine = "/usr/local/bin/runsc"
      runtime_root = "/run/containerd/runsc"
    [plugins.cri.containerd.gvisor]
      runtime_type = "io.containerd.runtime.v1.linux"
      runtime_engine = "/usr/local/bin/runsc"
      runtime_root = "/run/containerd/runsc"
EOF
```

> Untrusted workloads will be run using the gVisor (runsc) runtime.

Create the `containerd.service` systemd unit file:

```
$ cat <<EOF | sudo tee /etc/systemd/system/containerd.service
[Unit]
Description=containerd container runtime
Documentation=https://containerd.io
After=network.target

[Service]
ExecStartPre=/sbin/modprobe overlay
ExecStart=/bin/containerd
Restart=always
RestartSec=5
Delegate=yes
KillMode=process
OOMScoreAdjust=-999
LimitNOFILE=1048576
LimitNPROC=infinity
LimitCORE=infinity

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

### Configure the Kubelet

```
$ {
  sudo mv ${HOSTNAME}-key.pem ${HOSTNAME}.pem /var/lib/kubelet/
  sudo mv ${HOSTNAME}.kubeconfig /var/lib/kubelet/kubeconfig
  sudo mv ca.pem /var/lib/kubernetes/
}
```

Create the `kubelet-config.yaml` configuration file:

```
$ cat <<EOF | sudo tee /var/lib/kubelet/kubelet-config.yaml
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
authentication:
  anonymous:
    enabled: false
  webhook:
    enabled: true
  x509:
    clientCAFile: "/var/lib/kubernetes/ca.pem"
authorization:
  mode: Webhook
clusterDomain: "cluster.local"
clusterDNS:
  - "10.32.0.10"
podCIDR: "${POD_CIDR}"
resolvConf: "/run/resolvconf/resolv.conf"
runtimeRequestTimeout: "15m"
tlsCertFile: "/var/lib/kubelet/${HOSTNAME}.pem"
tlsPrivateKeyFile: "/var/lib/kubelet/${HOSTNAME}-key.pem"
EOF
```

> The `resolvConf` configuration is used to avoid loops when using CoreDNS for service discovery on systems running `systemd-resolved`.

Create the `kubelet.service` systemd unit file:

```
$ cat <<EOF | sudo tee /etc/systemd/system/kubelet.service
[Unit]
Description=Kubernetes Kubelet
Documentation=https://github.com/kubernetes/kubernetes
After=containerd.service
Requires=containerd.service

[Service]
ExecStart=/usr/local/bin/kubelet \\
  --config=/var/lib/kubelet/kubelet-config.yaml \\
  --container-runtime=remote \\
  --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock \\
  --image-pull-progress-deadline=2m \\
  --kubeconfig=/var/lib/kubelet/kubeconfig \\
  --network-plugin=cni \\
  --register-node=true \\
  --v=2
Restart=on-failure
RestartSec=5

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


### Configure the Kubernetes Proxy

```
$ sudo mv kube-proxy.kubeconfig /var/lib/kube-proxy/kubeconfig
```

Create the `kube-proxy-config.yaml` configuration file:

```
$ cat <<EOF | sudo tee /var/lib/kube-proxy/kube-proxy-config.yaml
kind: KubeProxyConfiguration
apiVersion: kubeproxy.config.k8s.io/v1alpha1
clientConnection:
  kubeconfig: "/var/lib/kube-proxy/kubeconfig"
mode: "iptables"
clusterCIDR: "10.200.0.0/16"
EOF
```

Create the `kube-proxy.service` systemd unit file:

```
$ cat <<EOF | sudo tee /etc/systemd/system/kube-proxy.service
[Unit]
Description=Kubernetes Kube Proxy
Documentation=https://github.com/kubernetes/kubernetes

[Service]
ExecStart=/usr/local/bin/kube-proxy \\
  --config=/var/lib/kube-proxy/kube-proxy-config.yaml
Restart=on-failure
RestartSec=5

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

### Start the Worker Services

```
$ {
  sudo systemctl daemon-reload
  sudo systemctl enable containerd kubelet kube-proxy
  sudo systemctl start containerd kubelet kube-proxy
}
```

> Remember to run the above commands on each worker node: `worker-1`, `worker-2`, and `worker-3`.


## Verification

> The virtual machines created in this tutorial will not have permission to complete this section. Run the following commands from the same machine used to create the compute instances.

List the registered Kubernetes nodes:

```
$ ssh -i ~/.ssh/id_rsa-k8s.pub 10.240.0.11 "kubectl get nodes --kubeconfig admin.kubeconfig"
```

> output

```
NAME       STATUS   ROLES    AGE   VERSION
worker-1   Ready    <none>   35s   v1.12.0
worker-2   Ready    <none>   36s   v1.12.0
worker-3   Ready    <none>   36s   v1.12.0
```

Next: [Configuring kubectl for Remote Access](10-configuring-kubectl.md)