Chapter 3. First Lab to create K8s cluster with one master and 2 worker nodes
Hello Everyone!
Let’s get our hands-on in K8s by creating a cluster environment of one master and 2 worker nodes.
Follow the below steps on Centos 7.x
The first thing that we are going to do is use SSH to log in to all machines. Once we have logged in, we need to elevate privileges using sudo.
sudo su
Disable SELinux.
setenforce 0 sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux
Enable the br_netfilter module for cluster communication.
modprobe br_netfilter echo '1' > /proc/sys/net/bridge/bridge-nf-call-iptables
Disable swap to prevent memory allocation issues.
swapoff -a vim /etc/fstab.orig -> Comment out the swap line
Install the Docker prerequisites.
yum install -y yum-utils device-mapper-persistent-data lvm2
Add the Docker repo and install Docker.
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo yum install -y docker-ce
Configure the Docker Cgroup Driver to systemd, enable and start Docker
sed -i '/^ExecStart/ s/$/ --exec-opt native.cgroupdriver=systemd/' /usr/lib/systemd/system/docker.service systemctl daemon-reload systemctl enable docker --now systemctl status docker docker info | grep -i cgroup
Add the Kubernetes repo.
cat <<EOF > /etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=0 repo_gpgcheck=0 gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg EOF
Install Kubernetes.
yum install -y kubelet kubeadm kubectl
Enable Kubernetes. The kubelet service will not start until you run kubeadm init.
systemctl enable kubelet
*Note: Complete the following section on the MASTER ONLY!
Initialize the cluster using the IP range for Flannel.
kubeadm init --pod-network-cidr=10.244.0.0/16
Copy the kubeadmin join command.
Exit sudo and run the following:
mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config
Deploy Flannel (network for Pod communication across the cluster)
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
Check the cluster state.
kubectl get pods --all-namespaces
*Note: Complete the following steps on the Worker NODES ONLY!
Run the join command that you copied earlier (this command needs to be run as sudo), then check your nodes from the master.
kubectl get nodes
P.S: Feel free to reach me in case of any doubts!
Happy Learning!
Shivani S.
