Deploy Kubernetes in Ubuntu 18.04 (Bionic Beaver)

Prerequisites:
Oracle Virtual Box VM
2 CPU, 4 GB RAM, 40 GB HD
Ubuntu 18.04
Network Interface: Bridge Adapter Mode & Host only Adapter

Install Packages:

Setup Docker

$ sudo apt-get update
$ sudo apt-get install -y docker.io curl
$ sudo systemctl enable docker
$ sudo systemctl start docker 
$ sudo groupadd docker 
$ sudo usermod -aG docker $USER
$ sudo docker info
$ sudo sysctl net.bridge.bridge-nf-call-iptables=1

Make sure Cgroup driver points to “systemd” and not to “Cgroupfs”

How to check Cgroup driver points to “systemd”
$ sudo docker info | grep Cgroup
How to change Cgroup driver to "systemd"
$ sudo systemctl status docker
Check following section 
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
$ sudo vi /lib/systemd/system/docker.service
Replace this line:
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
by:
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock --exec-opt native.cgroupdriver=systemd
Restart the Docker service by running the following command:
$ sudo systemctl daemon-reload
$ sudo systemctl restart docker
Verify the cgroups driver to systemd
$ sudo docker info | grep Cgroup

Setup Kubernetes Packages

$ curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add
$ sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"
$ sudo apt-get update
$ sudo apt-get install -y kubeadm kubelet kubectl
$ sudo apt-mark hold kubeadm kubelet kubectl
$ kubeadm version
$ sudo swapoff -a

Initialize Kubernetes on Master Node

$ sudo kubeadm init --pod-network-cidr=10.244.0.0/16
$ mkdir -p $HOME/.kube
$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

Bring up Pod Networking (Flannel CNI is used here)

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
If you want to use calico instead of flannel:
$ kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml
$ kubectl get pods --all-namespaces
$ kubectl get nodes
Following command will enable master node also to bring up the pods
$ kubectl taint nodes --all node-role.kubernetes.io/master-

Create a deployment and test

Create deployment.yaml
$ vi ngin-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
Create deployment
$ kubectl create -f ngin-deployment.yaml
Deployment can be alternatively created using this command. 
$ kubectl create deployment nginx-dep --image=nginx:1.14.2 
Later we can use following command to edit and update it
$ kubectl get deployment nginx-dep -o yaml > dep.yaml
Check pods
$ kubectl get pods
Check deployment
$ kubectl get deployments
Check replicasets
$ kubectl get replicasets

Create a service and access from browser

Create service
$ kubectl expose deployment nginx-deployment --type=LoadBalancer
--name=nginx-web-server
Check created services
$ kubectl get services
Use the <vm ip>:<node port> from above command to access nginx service from the host machine browser.

Troubleshooting Guide

Reset the kubeadm
$ sudo kubeadm reset
$ sudo rm -rf /var/lib/kubelet/pki
$ sudo swapoff -a
$ sudo sysctl net.bridge.bridge-nf-call-iptables=1
$ sudo rm -rf $HOME/.kube/config
$ kubectl taint nodes --all node-role.kubernetes.io/master-
To update the hostname
sudo vi /etc/hosts
127.0.1.1 <old hostname> <new hostname>
sudo hostnamectl set-hostname <new hostname>
Exit the vm and ssh again
Error: "The connection to the server 10.0.2.15:6443 was refused - did you specify the right host or port?"
sudo -i
swapoff -a
exit
strace -eopenat kubectl version