k8s-installation-kubeadm

Pre-requisite

• Master node - 2 cpu x 2 GB memory
  

• Worker node - 1 cpu x 2 GB memory
  

Pre-installation steps

The below steps will be performed on both master and worker node

• 1. Turn of Swap

apt-get update

swapoff -a

• 2. Comment swap FS from /etc/fstab

vi /etc/fstab

Comment any line that has swap written

• 3. Edit /etc/hostname and edit hostname to match the host of your choice
• 4. Get private ip address of all hosts

ip addr

• 5. Edit /etc/hosts to add hostname and IP address on all nodes

vi /etc/hosts

    kmaster 192.168.0.2  -- private IP address from previous step
    knode1  192.168.0.3  -- provate IP address from previous step 

Installation Procedure

Install kubelet kubeadm and kubectl

• Ubuntu

apt-get update && apt-get install -y apt-transport-https curl

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -

cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF

apt-get update

apt-get install -y kubelet kubeadm kubectl

apt-mark hold kubelet kubeadm kubectl

• Centos

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF

setenforce 0

sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

systemctl enable --now kubelet

Install Docker

• Ubuntu

sudo apt-get update

sudo apt-get install -y \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg-agent \
    software-properties-common

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

sudo apt-get update

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

• Centos

sudo yum install -y yum-utils \
  device-mapper-persistent-data \
  lvm2

sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

sudo yum install -y docker-ce docker-ce-cli containerd.io --nobest

systemctl start docker

Configure Cluster using kubeadm

The below steps will be performed ONLY ON MASTER NODE

• Get the IP address of master

ip addr

• Initialize the cluster

kubeadm init --pod-network-cidr=192.168.0.0/16 --apiserver-advertise-address={{IP_ADDR_MASTER}}

• Your output should look like below -

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

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 10.138.0.2:6443 --token 3ccgnq.2owa1scoiqqoqhdq \
    --discovery-token-ca-cert-hash sha256:04ff7a9148ae02db8a4be70f016fe66d6d5870ea09641e48f6a7db54747e1acd 

Preserve the above output as it contains the token required for node configuration.

• Copy over the configuration files

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

• Install Networking component (CNI)

kubectl apply -f https://docs.projectcalico.org/v3.8/manifests/calico.yaml

• Join the worker node

The below steps are to be run only on the worker node

The output of the kubeadm init command will provide the kubeadm join as its output. Run the kubeadm join command on the worker nodes.

kubeadm join 10.138.0.2:6443 --token 3ccgnq.2owa1scoiqqoqhdq \
    --discovery-token-ca-cert-hash sha256:04ff7a9148ae02db8a4be70f016fe66d6d5870ea09641e48f6a7db54747e1acd 

The output will be as below

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.