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Bootstrapping the Kubernetes Worker Nodes

In this lab you will bootstrap two Kubernetes worker nodes. The following components will be installed: runc, container networking plugins, containerd, kubelet, and kube-proxy.

Prerequisites

Copy Kubernetes binaries and systemd unit files to each worker instance:

for host in node-0 node-1; do
  SUBNET=$(grep $host machines.txt | cut -d " " -f 4)
  sed "s|SUBNET|$SUBNET|g" \
    configs/10-bridge.conf > 10-bridge.conf 
    
  sed "s|SUBNET|$SUBNET|g" \
    configs/kubelet-config.yaml > kubelet-config.yaml
    
  scp 10-bridge.conf kubelet-config.yaml \
  root@$host:~/
done

for host in node-0 node-1; do
  scp \
    downloads/runc.amd64 \
    downloads/crictl-v1.28.0-linux-amd.tar.gz \
    downloads/cni-plugins-linux-amd64-v1.3.0.tgz \
    downloads/containerd-1.7.8-linux-amd64.tar.gz \
    downloads/kubectl \
    downloads/kubelet \
    downloads/kube-proxy \
    configs/99-loopback.conf \
    configs/containerd-config.toml \
    configs/kubelet-config.yaml \
    configs/kube-proxy-config.yaml \
    units/containerd.service \
    units/kubelet.service \
    units/kube-proxy.service \
    root@$host:~/
done

The commands in this lab must be run on each worker instance: node-0, node-1. Login to the worker instance using the ssh command. Example:

ssh root@node-0

Provisioning a Kubernetes Worker Node

Install the OS dependencies:

{
  apt-get update
  apt-get -y install socat conntrack ipset
}

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

Disable Swap

By default, the kubelet will fail to start if swap is enabled. It is recommended that swap be disabled to ensure Kubernetes can provide proper resource allocation and quality of service.

Verify if swap is enabled:

swapon --show

If output is empty then swap is not enabled. If swap is enabled run the following command to disable swap immediately:

swapoff -a

To ensure swap remains off after reboot consult your Linux distro documentation.

Create the installation directories:

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:

{
  mkdir -p containerd
  tar -xvf crictl-v1.28.0-linux-amd.tar.gz
  tar -xvf containerd-1.7.8-linux-amd64.tar.gz -C containerd
  tar -xvf cni-plugins-linux-amd64-v1.3.0.tgz -C /opt/cni/bin/
  mv runc.amd64 runc
  chmod +x crictl kubectl kube-proxy kubelet runc 
  mv crictl kubectl kube-proxy kubelet runc /usr/local/bin/
  mv containerd/bin/* /bin/
}

Configure CNI Networking

Create the bridge network configuration file:

mv 10-bridge.conf 99-loopback.conf /etc/cni/net.d/

Configure containerd

Install the containerd configuration files:

{
  mkdir -p /etc/containerd/
  mv containerd-config.toml /etc/containerd/config.toml
  mv containerd.service /etc/systemd/system/
}

Configure the Kubelet

Create the kubelet-config.yaml configuration file:

{
  mv kubelet-config.yaml /var/lib/kubelet/
  mv kubelet.service /etc/systemd/system/
}

Configure the Kubernetes Proxy

{
  mv kube-proxy-config.yaml /var/lib/kube-proxy/
  mv kube-proxy.service /etc/systemd/system/
}

Start the Worker Services

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

Verification

The compute instances created in this tutorial will not have permission to complete this section. Run the following commands from the jumpbox machine.

List the registered Kubernetes nodes:

ssh root@server \
  "kubectl get nodes \
  --kubeconfig admin.kubeconfig"

NAME     STATUS   ROLES    AGE    VERSION
node-0   Ready    <none>   1m     v1.28.3
node-1   Ready    <none>   10s    v1.28.3

Next: Configuring kubectl for Remote Access

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