Setting up K8s cluster with Docker and Calico

This guide will walk you through the stages of installing a Kubernetes cluster with multiple worker nodes on Ubuntu using Docker as the container runtime and Calico as the network plugin. You'll also use Kubernetes to launch a dummy Nginx application.

Update and Upgrade:

Update the package list and upgrade existing packages:

sudo apt update
sudo apt upgrade -y

Disable Swap

Disable swap and update /etc/fstab:

sudo swapoff -a sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

Install Docker

Run the following commands on each machine (master and workers):

sudo apt-get remove docker docker-engine docker.io containerd runc
sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl software-properties-common
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update
sudo apt-get install -y docker-ce docker-ce-cli containerd.io

Start and Enable Docker:

Enable and start the Docker service:

sudo systemctl start docker
sudo systemctl enable docker

Install Kubernetes

Run the following commands on each machine (master and workers):

sudo apt-get update
sudo apt-get install -y apt-transport-https curl
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add –echo "deb https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl

Create the Kubernetes Cluster

Initialize the Master Node:

SSH into the master node.

Initialize the Kubernetes control plane and set the Pod network CIDR:

sudo kubeadm init --pod-network-cidr=192.168.0.0/16

Configure kube config and Calico:

On the master node, copy the kubeconfig file and set permissions:

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

Deploy the Calico network plugin:

kubectl apply -f https://raw.githubusercontent.com/projectcalico/calico/v3.25.0/manifests/calico.yaml

Join Worker Nodes:

SSH into each worker node and run the kubeadm join command provided by the master initialization output.

Deploy a Dummy Application

Create a Deployment YAML file (e.g., dummy-deployment.yaml):

apiVersion: apps/v1
kind: Deployment
metadata:
    name: dummy-deployment
spec:
    replicas: 3
    selector:
         matchLabels:
              app: dummy-app
    template:
         metadata:
              labels:
                   app: dummy-app
         spec:
              containers:
                -    name: nginx
                   image: nginx:latest

Apply the Deployment:

Apply the deployment configuration:

kubectl apply -f dummy-deployment.yaml

Verify the Deployment and Pods:

Check the status of the deployment and the created pods:

kubectl get deployments 
kubectl get pods

Your Kubernetes cluster is ready. I have used the most basic configuration for creating the cluster.

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For more details on creating the cluster, refer to the Kubernetes documentation.