Kubernetes 101 - Part1 - Create K8s cluster with kubeadm

Deploy 3 CentOS 7 VMs. One will be the master and the other two will be workers/ slaves.

Master is "m1" and workers are "w1" and "w2".

Plan IP address

192.168.105.100 - m1
192.168.105.101 - w1
192.168.105.102 - w2

Step1: on all 3 nodes

vi /etc/hosts

192.168.105.100 m1
192.168.105.101 w1
192.168.105.102 w2

Step2: on all 3 nodes

#Disable firewall

sudo firewall-cmd --state
sudo systemctl stop firewalld
sudo systemctl disable firewalld
sudo systemctl status firewalld

setenforce 0
sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux

Step3: on all 3 nodes

#Configure iptables for Kubernetes
cat <<EOF > /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

Step4: on all 3 nodes

#Disable swap

swapoff -a
vi /etc/fstab (Edit fstab file and comment(#) swap partition)

reboot all 3 nodes

Step5: on all 3 nodes

#configure 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=1

repo_gpgcheck=1

gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

EOF

Step6: Install docker on all 3 nodes

yum install docker -y

Step7: on all 3 nodes

yum install -y kubeadm kubectl kubelet --disableexcludes=kubernetes

systemctl daemon-reload
systemctl restart docker && systemctl enable --now docker
systemctl restart kubelet && systemctl enable --now kubelet

Step8: on master

kubeadm init --pod-network-cidr 10.244.0.0/16

Step9: on master

$ mkdir -p $HOME/.kube

$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

Step10: on master

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Step11: on all worker nodes

Use the join token from master to join worker nodes to the K8s cluster.

Example:

kubeadm join 192.168.105.100:6443 --token 4j1cjv.gcj2hx9suq5akc7v \

--discovery-token-ca-cert-hash sha256:b2ead930d772d8af2e45ca8c86c3895b092484c10f8034e52f917e71dc4c3fea

Hope it was useful. Cheers!

References

Why K8s on VMs?

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