Notes of Kubernetes Installation (by kubeadm)

Prepare the local working environment

System Initialization

• Turn off firewall
  # temporarily
systemctl stop firewalld
# permanently
systemctl disable firewalld
• Turn off selinux
  # temporarily
sed -i 's/enforcing/disabled/' /etc/selinux/config
# permanently
setenforce 0
• Turn off swap
  # temporarily
swapoff -a
# permanently (add hash (#) to the beginning of the swap partition line)
vim /etc/fstab
• Configure hostname
  hostnamectl set-hostname [hostname]

• Configure static IP
  vi /etc/sysconfig/network-scripts/ifcfg-ens32

  BOOTPROTO="static"
  IPADDR=192.168.8.20
  PREFIX0=24
  GATEWAY=192.168.8.2
  DNS1=114.114.114.114
  DNS2=8.8.8.8

• Add information of hosts (executed only on master node)

  cat >> /etc/hosts << EOF
  192.168.8.20 master01
  192.168.8.21 worker01
  192.168.8.22 worker02
  EOF

• IPv4 transist to iptables

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

  sysctl --system

• Synchronize time across cluster nodes
  yum install ntpdate -y
ntpdate time.windows.com

Software Installation

Docker

wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo

yum -y install docker-ce-18.06.1.ce-3.el7

systemctl enable docker && systemctl start docker

docker --version

Configure Yum Repository

Set the location of Repository

cat > /etc/docker/daemon.json << EOF
{
"registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"]
}
EOF

systemctl restart docker

Add the Repository

cat > /etc/yum.repos.d/kubernetes.repo << EOF
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

Kubeadm & Kubelet & kubectl

yum install -y kubelet-1.18.0 kubeadm-1.18.0 kubectl-1.18.0

systemctl enable kubelet

Depolyment of Master Node

# Exceuted only on master node

kubeadm init \
--apiserver-advertise-address=192.168.8.20 \
--image-repository registry.aliyuncs.com/google_containers \
--kubernetes-version v1.18.0 \
--service-cidr=10.96.0.0/12 \
--pod-network-cidr=10.244.0.0/16

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

kubectl get nodes

• Executed on the worker nodes:

  kubeadm join 192.168.8.20:6443 --token 4ephdf.8hz8xetf59ypi1tq \
    --discovery-token-ca-cert-hash sha256:a85072062388460e112209b012a67afd5f857781624c4ddfe25e3b406790270c

  

  The expire duration of token is 24 hours, to regenerate a token:

  kubeadm token create --print-join-command

  Then check the worker nodes on master
  

Depoly CNI plugin

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

kubectl get pods -n kube-system

Test Kubernetes Cluster

kubectl create deployment nginx --image=nginx

kubectl get pod

kubectl expose deployment nginx --port=80 --type=NodePort

kubectl get pod,svc

Can be accessed from worker nodes