ksrepo9/java_project

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.

##### Host file update
cat <<EOF>> /etc/hosts
10.0.0.1 master
10.0.0.2 worker1
10.0.0.3 worker2
EOF
  

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 <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-\$basearch
enabled=1
gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
exclude=kubelet kubeadm kubectl
EOF

Install Kubernetes components

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

Enable and Start kubelet service

sudo systemctl enable --now kubelet

On kmaster

Initialize Kubernetes Cluster

kubeadm init 

Deploy Calico 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

Troubleshooting

rm /etc/containerd/config.toml
systemctl restart containerd
kubeadm init