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kubeadm-installation-centos7.md

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Install Kubernetes Cluster using kubeadm

Follow this documentation to set up a Kubernetes cluster on CentOS 7.

This documentation guides you in setting up a cluster with one master node and one worker node.

Assumptions

Role FQDN IP OS RAM CPU
Master kmaster.example.com 172.16.16.100 CentOS 7 2G 2
Worker kworker.example.com 172.16.16.101 CentOS 7 1G 1

On both Kmaster and Kworker

Perform all the commands as root user unless otherwise specified

Disable Firewall
systemctl disable firewalld; systemctl stop firewalld
Disable swap
swapoff -a; sed -i '/swap/d' /etc/fstab
Disable SELinux
setenforce 0
sed -i --follow-symlinks 's/^SELINUX=enforcing/SELINUX=disabled/' /etc/sysconfig/selinux
Update sysctl settings for Kubernetes networking
cat >>/etc/sysctl.d/kubernetes.conf<<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system
Install docker engine
yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
yum install -y docker-ce-19.03.12
systemctl enable --now docker

Kubernetes Setup

Add yum repository
cat >>/etc/yum.repos.d/kubernetes.repo<<EOF
[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
Install Kubernetes components
yum install -y kubeadm-1.18.5-0 kubelet-1.18.5-0 kubectl-1.18.5-0
Enable and Start kubelet service
systemctl enable --now kubelet

On kmaster

Initialize Kubernetes Cluster
kubeadm init --apiserver-advertise-address=<kube-master-ip> --pod-network-cidr=192.168.0.0/16   --ignore-preflight-errors=all
Deploy Calico network (overlay network)
kubectl --kubeconfig=/etc/kubernetes/admin.conf create -f https://docs.projectcalico.org/v3.14/manifests/calico.yaml
Cluster join command
kubeadm token create --print-join-command
To be able to run kubectl commands as non-root user

If you want to be able to run kubectl commands as non-root user, then as a non-root user perform these

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

On Kworker

Join the cluster

Use the output from kubeadm token create command in previous step from the master server and run here.

Verifying the cluster

Get Nodes status
kubectl get nodes
Get component status
kubectl get cs