Installing Kubernetes Cluster on Ubuntu Server

sudo apt update
sudo apt upgrade

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

sudo tee /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF
sudo modprobe overlay
sudo modprobe br_netfilter

sudo tee /etc/sysctl.d/kubernetes.conf <<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF

sudo sysctl --system

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

sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmour -o /etc/apt/trusted.gpg.d/docker.gpg
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

sudo apt update
sudo apt install -y containerd.io

containerd config default | sudo tee /etc/containerd/config.toml >/dev/null 2>&1
sudo sed -i 's/SystemdCgroup \= false/SystemdCgroup \= true/g' /etc/containerd/config.toml

sudo systemctl restart containerd
sudo systemctl enable containerd

   sudo apt update
   # apt-transport-https may be a dummy package; if so, you can skip that package
   sudo apt install -y apt-transport-https ca-certificates curl gpg

  # If the directory `/etc/apt/keyrings` does not exist, it should be created before the curl command, read the note below.
    # sudo mkdir -p -m 755 /etc/apt/keyrings
    curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.29/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg

    # This overwrites any existing configuration in /etc/apt/sources.list.d/kubernetes.list
    echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.29/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list

    sudo apt update
    sudo apt install -y kubelet kubeadm kubectl
    sudo apt-mark hold kubelet kubeadm kubectl

sudo systemctl enable --now kubelet

#change the cidr ip range, depends on your network,
# ensure not clash with your Range / subnet IP network
#default calico cidr
#sudo kubeadm init —pod-network-cidr=192.168.0.0/16

# in my case, my ip network range is 192.168.0.0/24
# i change my cidr to 10.10.0.0/16

#notes :
# If you install in cloud instances and have public ip do this instead
# sudo kubeadm init --apiserver-cert-extra-sans=your-public-ip --apiserver-advertise-address=your-public-ip --control-plane-endpoint=your-public-ip:6443 --pod-network-cidr=xx.xx.xx.xx/xx --node-name your-node-name

# Explanation :
# --apiserver-cert-extra-sans => When initializing a Kubernetes cluster with kubeadm, if you plan to access the API server via its public IP address or any additional DNS names, you should use the --apiserver-cert-extra-sans flag. This ensures that the certificate used by the API server includes these addresses, avoiding certificate validation errors.

# --apiserver-advertise-address :
# Definition:
# This flag specifies the IP address that the Kubernetes API server will advertise to nodes and other # # components in the cluster.
# Use Case:
# You would use this flag to set the IP address of the API server explicitly. This is useful in environments where your machine has multiple network interfaces or IP addresses, and you need to specify which one should be used.

# --control-plane-endpoint
# Definition:
# This flag specifies a stable IP address or DNS name for the control plane. It is particularly useful in highly available (HA) setups where multiple control plane nodes are behind a load balancer.
# Use Case:
# In a highly available Kubernetes cluster, you typically have multiple control plane nodes behind a load balancer. You can use this flag to set the load balancer's address or DNS name as the control plane endpoint. This ensures that all the components use a stable address to communicate with the API server.

# In GCP use this command 
# sudo kubeadm init --apiserver-cert-extra-sans=35.226.75.54 --pod-network-cidr=192.168.0.0/16 --control-plane-endpoint=35.226.75.54:6443 --node-name masternode -v=9

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

    kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.2/manifests/tigera-operator.yaml

curl https://raw.githubusercontent.com/projectcalico/calico/v3.27.2/manifests/custom-resources.yaml -O

vi custom-resources.yaml

# in my case change the subnet/ CIDR section from 192.168.0.0/16 to 10.10.0.0/16

kubectl apply -f custom-resources.yaml```

watch kubectl get pods -n calico-system

NAMESPACE     NAME                READY   STATUS                  RESTARTS         AGE
kube-system   calico-node-txngh   1/1     Running                   0              54s

kubeadm token create --print-join-command