How to Setup Kubernetes Cluster on Debian 11

title: 'How to Setup Kubernetes Cluster on Debian 11' sub_title: 'How to Setup Kubernetes Cluster on Debian 11' meta_description: 'In this post, we will show you how to install and configure Kubernetes cluster on Debian 11' status: 'public' created_at: '2021-10-20 12:01:00' path: 'overview' author_name: 'Simon Bennett' author_email: 'simon@snapshooter.io'

Introduction

Kubernetes also known as k8s is a free and open-source container orchestration tool used for managing containerized applications. It is developed by Google and allows you to orchestrate containers across multiple hosts. With Kubernetes, you can set up load balancing between containers and run multiple containers across multiple systems. It can run on-premises bare metal, OpenStack, public clouds Google, Azure, AWS, etc.

Features

• Automated deployment and scheduling

• Automated rollouts & rollback

• Horizontal Scaling & Load Balancing

• Self-Healing Capabilities

• Provide an in-built tool for logging and monitoring

In this guide, we will explain how to set up Kubernetes cluster on Debian 11.

Requirements

• Two server running Debian 11 operating system.

• A root password is set up on your server.

Getting Started

Before starting, Swap space must be disabled in your system. You can disable it by editing the /etc/fstab file:

nano /etc/fstab

Comment the following line:

# swap was on /dev/sda6 during installation # UUID=18b43798-486f-499d-9edf-2c551b34b5a1 none swap sw 0 0

Save and close the file then disable the Swap space on the fly using the following command:

swapoff -a

Next, you will also need to enable IP forwarding. You can do it by editing /etc/sysctl.conf file.

nano /etc/sysctl.conf

Uncomment the following line:

net.ipv4.ip_forward=1

Save and close the file when you are finished.

Install Docker CE on both Master and Worker Node

Next, you will need to install Docker CE on both the Master and Worker nodes. First, install all the required dependencies using the following command:

apt-get install apt-transport-https ca-certificates curl gnupg2 software-properties-common

Next, add the Docker CE repository with the following command:

curl -fsSL https://download.docker.com/linux/debian/gpg | 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/debian $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list

Next, update the repository and install the Docker CE with the following command:

apt-get update -y apt-get install docker-ce docker-ce-cli containerd.io -y

Once Docker CE has been installed, verify the installed version of Docker CE with the following command:

docker -v

You will get the following output:

Docker version 20.10.9, build c2ea9bc

Install Kubernetes Components on Both Master and Worker Node

Next, you will also need to install the Kubernetes component on both nodes. First, add the Kubernetes repository using the following command:

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

Next, update the repository and install all required components using the following command:

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

Once all the Kubernetes packages are installed, you can proceed to the next step.

Initialize Kubernetes Cluster

Next, you will need to initialize the Kubernetes cluster on the Master node. You can initialize it with the following command:

kubeadm init

You will get the following output:

Your Kubernetes control-plane has initialized successfully! To start using your cluster, you need to run the following as a regular user: mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config Alternatively, if you are the root user, you can run: export KUBECONFIG=/etc/kubernetes/admin.conf You should now deploy a pod network to the cluster. Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at: https://kubernetes.io/docs/concepts/cluster-administration/addons/ Then you can join any number of worker nodes by running the following on each as root: kubeadm join 69.28.91.245:6443 --token 3kwruw.iz4wiwbnr1l31o6t \ --discovery-token-ca-cert-hash sha256:c199b45b1abffe99f8ec539d5c6681a8857aac51b423a4e4efebf9ad86b86705

Next, run the following command to activate the kubernetes configuration:

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

Note: Remember the command kubeadm join from the above output. You will need to run it on the Worker node to join the cluster.

Join Worker Node to the Kubernetes Cluster

Next, go to the Worker node and run the following command to join the Kubernetes cluster:

kubeadm join 69.28.91.245:6443 --token 3kwruw.iz4wiwbnr1l31o6t \ --discovery-token-ca-cert-hash sha256:c199b45b1abffe99f8ec539d5c6681a8857aac51b423a4e4efebf9ad86b86705

You will get the following output:

This node has joined the cluster: * Certificate signing request was sent to apiserver and a response was received. * The Kubelet was informed of the new secure connection details. Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

Verify the Cluster Status

Now, go to the Master node and run the following command verify the Worker node.

kubectl get nodes

You should see the following output:

NAME STATUS ROLES AGE VERSION master Ready control-plane,master 8m30s v1.22.2 worker Ready <none> 6m12s v1.22.2

As you can see, both worker and master node have joined the cluster.

Deploy Calico Pod Network Add-on

Next, you will need to install the Calico pod network add-on on the Master node. You can install it using the following command:

kubectl apply -f https://docs.projectcalico.org/v3.16/manifests/calico.yaml

Now, verify the status of pods from all namespaces using the following command:

kubectl get pods --all-namespaces

You will get the following output:

NAMESPACE NAME READY STATUS RESTARTS AGE kube-system calico-kube-controllers-677965bf5-8nqxn 0/1 Error 2 (34s ago) 76s kube-system calico-node-6qhqm 1/1 Running 0 80s kube-system calico-node-x7sm8 1/1 Running 0 80s kube-system coredns-78fcd69978-8zllm 1/1 Running 0 8m42s kube-system coredns-78fcd69978-hxzfw 1/1 Running 0 8m42s kube-system etcd-master 1/1 Running 0 8m48s kube-system kube-apiserver-master 1/1 Running 0 8m45s kube-system kube-controller-manager-master 1/1 Running 0 8m45s kube-system kube-proxy-78pck 1/1 Running 0 6m31s kube-system kube-proxy-sgqz5 1/1 Running 0 8m43s kube-system kube-scheduler-master 1/1 Running 0 8m45s

Verify Kubernetes Cluster

Next, you will need to test whether the Kubernetes cluster is working or not.

To test it, let's create an Nginx deployment using the following command:

kubectl create deployment nginx-web --image=nginx --port=80

Next, verify your Nginx deployment using the following command:

kubectl get deployments.apps -o wide

You will get the following output:

NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR nginx-web 0/1 1 0 6s nginx nginx app=nginx-web

Next, scale your deployment with 3 replica using the following command:

kubectl scale --replicas=3 deployment nginx-web

Now verify the status of your deployment using the following commands,

kubectl get deployments.apps nginx-web

Sample output:

NAME READY UP-TO-DATE AVAILABLE AGE nginx-web 3/3 3 3 40s

Next, run the following command to create a pod for Nginx deployment.

kubectl run nginx-web --image=httpd --port=80

Next, create an Nginx service and expose it on port 80.

kubectl expose pod nginx-web --name=http-service --port=80 --type=NodePort

You can now check the Nginx service using the following command:

kubectl get service http-service

Sample output:

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE http-service NodePort 10.103.75.66 <none> 80:30844/TCP 36s

Next, get detailed information about the Nginx service using the command below:

kubectl describe service http-service

You will get the following output:

Name: http-service Namespace: default Labels: run=nginx-web Annotations: <none> Selector: run=nginx-web Type: NodePort IP Family Policy: SingleStack IP Families: IPv4 IP: 10.103.75.66 IPs: 10.103.75.66 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 30844/TCP Endpoints: 192.168.171.75:80 Session Affinity: None External Traffic Policy: Cluster Events: <none>

You can check your running Nginx pods using the following command:

kubectl get pods nginx-web -o wide

Sample output:

NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx-web 1/1 Running 0 106s 192.168.171.75 worker <none> <none>

Now, you can verify the Nginx server by specifying the Worker node's IP address as shown below:

curl http://worker-node-ip:30844

If everything is fine, you will get the following output:

<html><body><h1>It works!</h1></body></html>

Conclusion

In the above guide, you learned how to set up a Kubernetes cluster on Debian 11. You can now add more Worker nodes to the Kubernetes cluster and scale your application as per your requirement.