First of all, we should have three instances created that can connect over the public network. It doesn't matter how those instances are created, for example, they can either be Digital Ocean droplets
or AWS EC2
instances.
Once you are into those instances, the commands that are mentioned below should be run on all the instances
# Get sudo working
sudo -l
# update packages and their version
sudo apt-get update && sudo apt-get upgrade -y
# install curl and apt-transport-https
sudo apt-get update && sudo apt-get install -y apt-transport-https curl
# add key to verify releases
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
# add kubernetes apt repo
cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF
# install kubelet, kubeadm and kubectl
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
# install docker
sudo apt-get install docker.io
sudo apt update
sudo apt install apt-transport-https ca-certificates curl gnupg-agent software-properties-common
Import the repository’s GPG key using the following curl command:
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
Add the Docker APT repository to your system:
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
To install the latest version of Docker, run the commands below
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io
To install a specific version, first list all the available versions in the Docker repository:
sudo apt update
apt list -a docker-ce
output
docker-ce/focal 5:19.03.9~3-0~ubuntu-focal amd64
sudo apt install docker-ce=<VERSION> docker-ce-cli=<VERSION> containerd.io
Check docker status
sudo systemctl status docker
# apt-mark hold is used so that these packages will not be updated/removed automatically
sudo apt-mark hold kubelet kubeadm kubectl
After the above commands are successfully run on all the worker nodes. Below steps can be followed to initialize the Kubernetes cluster.
Run the below command on the node that you want to make the leader node. Please make sure you replace the correct IP of the node with IP-of-Node
export MASTER_IP=<IP-of-Node>
kubeadm init --apiserver-advertise-address=${MASTER_IP} --pod-network-cidr=10.244.0.0/16
###Configure docker's cgroup driver
There are chances that the kubeadm init command is going to fail saying the different cgroup drvers are being used in the kubelet (systemd) and docker (cgroupfs) service. To resolve that we will make sure that both the services are running with the same cgroup driver.
It's recommended that we use systemd as cgroup driver for both of the services. To restart docker with systemd as cgroup driver, change the service file (/lib/systemd/system/docker.service) for docker to accept cgroup driver
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock --exec-opt native.cgroupdriver=systemd
and then restart the docker service
systemctl daemon-reload
systemctl restart docker You will have to do this on all the other instances as well.
Once the command kubeadm init
is completed on the leader node, below we would get a command like below in the output of kubeadm init
that can be run on worker nodes to make them join the leader node.
kubeadm join 206.189.134.39:6443 --token dxxfoj.a2zzwbfrjejzir4h \
--discovery-token-ca-cert-hash sha256:110e853989c2401b1e54aef6e8ff0393e05f18d531a75ed107cf6c05ca4170eb
You can also run the below cluster join command
kubeadm token create --print-join-command
The below command can be run on the leader node to install the CNI plugin
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
After successful completion of kubeadm init
command, like we got the kubeadm join
command, we would also get details about how we can set up kubeconfig
file.
For a Root User
export KUBECONFIG=/etc/kubernetes/admin.conf
For Non Root User run the below commands
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown