Logical Topology

Requirements
https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

Workflow

1. Networking and firewall setup.
   Execute on each node with root user.
   

   ## Mapping node-name in /etc/hosts.
   cat > /etc/hosts
   10.10.10.2  kubernetes.maste
   10.10.10.3  kubernetes.worker01
   10.10.10.4  kubernetes.worker02
   
   ## Adding user with sudo privilleges. 
   adduser kubernetes
   passwd kubernetes
   usermod -a -G sudo kubernetes
   
   ## Disabling ufw service. 
   systemctl stop ufw
   systemctl disable ufw
   
   ## Disabling swap support. 
   swapoff -a
   
   ## Allowing required ports.
   Depend on your firewall environment.
   You need to open port 6443, 2379-2380, 10250-10252 on master node.
   You need to open port 10250, and 30000-32767 on worker node.

2. Node preparation.
   Execute on each node with kubernetes user.
   

   ## Update and upgrading system.
   sudo apt update -y; sudo apt upgrade -y; sudo apt autoremove
   
   ## Install required packages and docker
   sudo apt install -y docker.io; sudo docker version
   sudo apt install -y apt-transport-https; curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
   
   ## Adding kubernetes repository.
   sudo echo "deb http://apt.kubernetes.io/kubernetes-xenial main" > kubernetes.list 
   sudo mv kubernetes.list /etc/apt/sources.list.d/kubernetes.list
   
   ## Install kubectl, kubelet, and kubeadm.
   sudo apt update -y; sudo apt install -y kubectl kubelet kubeadm
   sudo apt-mark hold kubelet kubeadm kubectl

3. Kubernetes master setup.
   Execute on master node with kubernetes user.
   

   ## Master initialization
   sudo kubeadm init --pod-network-cidr=10.244.10.0/16
   
   ## Copy configuration
   mkdir -p $HOME/.kube 
   sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
   sudo chown $(id -u):$(id -g) $HOME/.kube/config
   
   ## Install POD Network flannel
   wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
   kubectl apply -f kube-flannel.yml
   watch -n1 kubectl get pods --all-namespaces ##wait until all pods state became ready
   
   ## Displaying token and token-ca-cert-hash for worker initialization.
   sudo kubeadm token list
   sudo openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'

4. Kubernetes worker setup.
   Execute on worker node with kubernetes user.
   

   ## Join to master
   sudo kubeadm join --token [TOKEN] [NODE-MASTER]:6443 --discovery-token-ca-cert-hash sha256:[TOKEN-CA-CERT-HASH]

5. Kubernetes cluster verification.
   Execute on maser node with kubernetes user.
   

   kubectl config view 
   kubectl cluster-info 
   kubectl get nodes

6. Kubernetes Dashboard Setup.
   Execute on master node with kubernetes user.
   

   ## Installation
   kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.0.0-beta4/aio/deploy/recommended.yaml 
   
   ## Verificition
   kubectl get svc --all-namespaces -o wide
   kubectl -n kubernetes-dashboard get svc
   
   ## Exposing Kubernetes Dashboard
   ## Change type: ClusterIP to NodePort.
   kubectl -n kubernetes-dashboard edit svc kubernetes-dashboard 
   kubectl get svc --all-namespaces -o wide
   
   ## Set Permissive RBAC Permission
   kubectl create clusterrolebinding permissive-binding --clusterrole=cluster-admin --user=admin --user=kubelet --group=system:serviceaccounts
   
   ## Accessing Kubernetes Dashboard
   kubectl get secrets; kubectl describe secrets [secret-name]
   kubectl --kubeconfig config/admin.conf -n kube-system describe secret $(kubectl --kubeconfig config/admin.conf -n kube-system get secret | grep admin-user | awk '{print $1}')