Continuation of Part 1 in Setting up a Kubernetes cluster on a local environment. In this we will install Kubeadm, Kubectl and Kubelet along with Flannel, the networking tool which is required to set up the cluster. In addition to that, Docker will also be installed which enables us to deploy and run containerised apps within the cluster.

Prerequisites

Completed the set up of master and worker VMs covered in Part 1.
VMs are powered up and can be accessed via SSH.

Step 1: Installing Docker (execute on all nodes)

Update and install packages:

sudo apt-get update
sudo apt-get install ca-certificates curl gnupg lsb-release

Adding the Docker official GPG key:

sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

Setting up the repository:

echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

Installing the latest version of Docker:

 sudo apt-get update
 sudo apt-get install docker-ce docker-ce-cli containerd.io docker-compose-plugin

Verifying the Docker installation:

sudo docker run hello-world

Step 2: Installing kubeadm, kubelet and kubectl (execute on all nodes)

Update and install transport-https package:

sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl

Downloading the Google Cloud public signing key:

sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg

Adding the Kubernetes repository:

echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list

Installing kubelet, kubeadm and kubectl:

sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl

Step 3: Configuring the master node (execute only on master node)

Before running the kubeadm init command, we might need to run the following 2 command if the issue discussed here is encountered.

sudo rm /etc/containerd/config.toml
sudo systemctl restart containerd

Running the kubeadm init command.

sudo kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=198.168.56.2

The IP address of --apiserver-advertise-address must match the IP which we've already set up for internal communication between the cluster nodes in Step 10 of Part 1 (i.e. the IP address allocated for the enp0s8 interface). In this case [198.168.56.2].

Also it is important make sure that the value assigned for --pod-network-cidr matches the Network of net-conf.json section in Flannel script which we will execute in Step 4. For instance the script has the value 10.244.0.0/16 as shown below.

Once completed successfully, it should output a token similar to below which we are going to use later to join other nodes with the master.

Additionally, if you want to run kubectl as "regular" user run the following commands.

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Step 4: Initialising the POD network (execute only on master node)

Using Flannel network plugin to set up the POD network

sudo kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

We should now be able to confirm the PODs in kube-system are all healthy once the installation is completed.

kubectl get pods --all-namespaces

Step 5: Joining the worker nodes to master (execute only on worker node).

In this step, we'll be joining the worker node created in Part 1 with the master.

Before the join command, we may need to run the following command as performed in Step 3 to resolve the issue discussed.

sudo rm /etc/containerd/config.toml
sudo systemctl restart containerd

Then run the join commands generated at the end of Step 3.

kubeadm join 198.168.56.2:6443 --token ryzhtg.t6mrkzlokvtltuoi  --discovery-token-ca-cert-hash sha256:1d3b4ec190419c6a3e01c9c38f2c1820ef65ad8417667b8266c35708b14c94a4

Go to the master and see if it has been joined successfully.

kubectl get nodes

That's it! and we now have a fully functional K8s cluster running in the local environment.