KUBERNETES-INSTALLATION

#KUBERNETES INSTALLATION SCRIPT IN UBUNTUX
#!/bin/bash
sudo hostnamectl set-hostname k8s-master
sudo -i
# copy this script and run in all master and worker nodes
#i1) Switch to root user [ sudo -i]
sudo hostnamectl set-hostname  node1
#2) Disable swap & add kernel settings
swapoff -a
sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab
#3) Add  kernel settings & Enable IP tables(CNI Prerequisites)
cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
overlay
br_netfilter
EOF
modprobe overlay
modprobe br_netfilter
cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
EOF
sysctl --system
#4) Install containerd run time
#To install containerd, first install its dependencies.
apt-get update -y
apt-get install ca-certificates curl gnupg lsb-release -y
#Note: We are not installing Docker Here.Since containerd.io package is part of docker apt repositories hence we added docker repository & it's key to download and install containerd.
# Add Docker’s official GPG key:
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
#Use follwing command to set up the repository:
echo \
  "deb [arch=$(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
# Install containerd
apt-get update -y
apt-get install containerd.io -y
# Generate default configuration file for containerd
#Note: Containerd uses a configuration file located in /etc/containerd/config.toml for specifying daemon level options.
#The default configuration can be generated via below command.
containerd config default > /etc/containerd/config.toml
# Run following command to update configure cgroup as systemd for contianerd.
sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' /etc/containerd/config.toml
# Restart and enable containerd service
systemctl restart containerd
systemctl enable containerd
#5) Installing kubeadm, kubelet and kubectl
# Update the apt package index and install packages needed to use the Kubernetes apt repository:
apt-get update
apt-get install -y apt-transport-https ca-certificates curl
# Download the Google Cloud public signing key:
curl -fsSL https://dl.k8s.io/apt/doc/apt-key.gpg | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-archive-keyring.gpg
# Add the Kubernetes apt repository:
echo "deb [signed-by=/etc/apt/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
# Update apt package index, install kubelet, kubeadm and kubectl, and pin their version:
apt-get update
apt-get install -y kubelet kubeadm kubectl
# apt-mark hold will prevent the package from being automatically upgraded or removed.
apt-mark hold kubelet kubeadm kubectl
# Enable and start kubelet service
systemctl daemon-reload
systemctl start kubelet
systemctl enable kubelet.service
#Initialised the control plane in the master node as the root user.
# Initialize Kubernetes control plane by running the below commond as root user.
sudo kubeadm init
#exit as root user  by running
sudo su - ubuntu
#execute the below commands as a normal ubuntu user by running
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
#To verify, if kubectl is working or not, run the following command.
kubectl get pods -A
#deploy the network plugin - weave network and verify
kubectl apply -f https://github.com/weaveworks/weave/releases/download/v2.8.1/weave-daemonset-k8s.yaml
kubectl get pods -A
kubectl get node