Install Kubernetes on Ubuntu

To install Kubernetes on Ubuntu, you can use the kubeadm tool, which simplifies the process of setting up a cluster. Here’s a step-by-step guide to install Kubernetes on Ubuntu.

Kubernetes Requirements

• Master Node.

• Worker Node 1.

• The host OS is Ubuntu Server.

1. Update Ubuntu Server

It is always an updated system package. use the command line below:

$ sudo apt update

2. Install Docker on Ubuntu Server

$ sudo apt install curl -y
$ curl -fsSL https://get.docker.com -o get-docker.sh
$ sh get-docker.sh
$ sudo usermod -aG docker $USER
$ docker --version

Repeat on all other nodes.

3. Install Kubernetes on Ubuntu server.

Use the command line to install K8s as below.

$ sudo apt-get install -y apt-transport-https ca-certificates curl
$ sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg

Repeat for each server node.

4. Add software repositories

k8s are not included in the default repositories. Use the command line below:

$ 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
$ sudo apt-get update

Repeat for each server node.

5. Install the tool for Kubernetes

A tool that helps to initialize a cluster using Kubernetes Admin or Kubeadm. Kubelet is the worker package, which runs on all nodes and starts containers. Use the command line below

$ sudo apt-get install -y kubeadm kubelet kubectl
$ sudo apt-mark hold kubelet kubeadm kubectl

Repeat for each server node.

6. Disabling swap memory on each server

$ sudo swapoff -a

7. Setting a unique hostname for each server node.

Decide which server to set as the primary node.

$ sudo hostnamectl set-hostname k8s-master

Next, Set a worker node hostname

$ sudo hostnamectl set-hostname k8s-node1

If you add a worker node, set a unique hostname on each one.

8. Initialize Kubernetes on the master node

On the master node, Run the command below:

$ sudo kubeadm init --apiserver-advertise-address=192.168.56.11 --pod-network-cidr=10.100.0.0/16

The output terminal is as below:

vagrant@k8s-master:~$ sudo kubeadm init --apiserver-advertise-address=192.168.56.11 --pod-network-cidr=10.100.0.0/16
[init] Using Kubernetes version: v1.24.2
[preflight] Running pre-flight checks
        [WARNING SystemVerification]: missing optional cgroups: blkio
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.56.11]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.56.11 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.56.11 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[apiclient] All control plane components are healthy after 4.501962 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node k8s-master as control-plane by adding the labels: [node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node k8s-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule node-role.kubernetes.io/control-plane:NoSchedule]
[bootstrap-token] Using token: 8ke6fa.3c5ll272057418qj
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

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 192.168.56.11:6443 --token 8ke6fa.3c5ll272057418qj \
        --discovery-token-ca-cert-hash sha256:4e69979a597f673781606eb7ab6bed5ccb741f46756b17f196b9cd76d3b51053

This is used to join the worker nodes to the cluster. We will create a directory for the cluster.

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

9. Deploy the pod network to the cluster.

A pod network allows communication between different nodes in the cluster. For example, Use the flannel virtual network. Use the command line below

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

Verify working and communicating

# kubectl get all -A

Join the worker node to Cluster.

The syntax:

kubeadm join --token <token> <control-plane-host>:<control-plane-port> --discovery-token-ca-cert-hash sha256:<hash>

Use kubeadm join command on each worker node to join it to the cluster.

$ sudo kubeadm join 192.168.56.11:6443 --token 8ke6fa.3c5ll272057418qj \
        --discovery-token-ca-cert-hash \
sha256:4e69979a597f673781606eb7ab6bed5ccb741f46756b17f196b9cd76d3b5105

Waiting minutes, You can check the status of the nodes. Switch to the Master node and run the command line as below:

kubectl get nodes

Conclusion

You have successfully installed Kubernetes on Ubuntu. I hope will this your helpful. Thank you for reading the DevopsRoles page! Install Kubernetes on Ubuntu, Install Kubernetes on Ubuntu.