Installing and Configuring Kubernetes Nodes

Install and configure Kubernetes on the management and compute nodes in the cluster.

Changing the Host Name and Mapping

Perform the operations on all management and compute nodes.

Set the host name of each node.
Management node:
```
hostnamectl set-hostname master
```
Compute node 1:
```
hostnamectl set-hostname compute01
```
Compute node 2:
```
hostnamectl set-hostname compute02
```
After the setting is complete, log in to the OS again for the change to take effect.
Modify the hosts files on all nodes.
1. Open the hosts file.
```
vi /etc/hosts
```
2. Press i to enter the insert mode and add the IP addresses and host names of all nodes in the cluster to the configuration file.
```
192.168.1.11 master
192.168.1.12 compute01
192.168.1.13 compute02
```
  See the result:
3. Press Esc, type :wq!, and press Enter to save the file and exit.

Installing the Base Components

Disable the firewall.

systemctl stop firewalld && systemctl disable firewalld

Install Docker.

yum install -y docker
cat <<EOF > /etc/docker/daemon.json
{
        "exec-opts": ["native.cgroupdriver=systemd"]
}
EOF
systemctl daemon-reload
systemctl restart docker

Enable the NET.BRIDGE.BRIDGE-NF-CALL-IPTABLES kernel option.
```
sysctl -w net.bridge.bridge-nf-call-iptables=1
```
Disable the swap partition.
1. Disable the swap partition.
```
swapoff -a
```
1. Open the /etc/fstab file.
```
vi /etc/fstab
```
2. Press i to enter the insert mode and comment out the swap partition information.
```
# /dev/mapper/openeuler-swap none                    swap    defaults        0 0
```
3. Press Esc to exit the insert mode. Type :wq! and press Enter to save the file and exit.

Install Kubernetes.

yum install -y kubelet kubeadm kubectl kubernetes-cni

If the above command fails to be executed, run the following command:

yum install -y kubelet kubeadm kubectl kubernetes-cni --nobest

Check the Kubernetes installation status.

rpm -qa | grep kubelet 
rpm -qa | grep kubeadm 
rpm -qa | grep kubectl 
rpm -qa | grep kubernetes-cni

Configure iptables.

echo "net.bridge.bridge-nf-call-iptables=1" > /etc/sysctl.d/k8s.conf

Enable the kubelet service.
```
systemctl enable kubelet
```

Configuring NTP

Configure NTP to synchronize the time between nodes in the cluster.

Install chrony and set the time zone on all nodes. In this document, an Asian time zone is used as an example.
```
yum install -y chrony
timedatectl set-timezone Asia/Shanghai
```
Set the management node as the NTP server node.
1. Open the /etc/chrony.conf file.
```
vi /etc/chrony.conf
```
2. Press i to enter the insert mode and add the following content:
```
allow 192.168.1.0/24
local stratum 10
```
  Replace the example network segment 192.168.1.0/24 with the actual one.
1. Press Esc to exit the insert mode. Type :wq! and press Enter to save the file and exit.
Configure compute nodes as NTP clients.
1. Open the /etc/chrony.conf file.
```
vi /etc/chrony.conf
```
2. Press i to enter the insert mode and comment out the following line:
```
pool pool.ntp.org iburst
```
  The following figure shows the modification result:
  
  Add the following content:
```
server master iburst
```
3. Press Esc to exit the insert mode. Type :wq! and press Enter to save the file and exit.

Start the NTP service.

Start the NTP service on all nodes and check the service status.

systemctl enable chronyd.service 
systemctl start chronyd.service 
systemctl status chronyd.service

Start NTP synchronization on all nodes.

timedatectl set-ntp no
timedatectl set-ntp yes

Verify time synchronization.
```
chronyc sources
```
The clock source on the compute node is master:

Run the date command on each node to check whether the time is the same.
```
date
```

Downloading Other Components Using Docker

Perform the following steps on all nodes in the cluster.

View the image list and determine the Docker image version to be downloaded.
```
kubeadm config images list
```
- Different versions of Kubernetes may require different versions of Docker images. Therefore, you need to view the image list and select the right Docker image version. The Docker image version used in 2 is for reference only.
- Ensure that the downloaded Docker image supports the Arm architecture.

Download the image from Docker Hub.

If openEuler 22.03 is used, you are advised to install Kubernetes 1.23.1.

docker pull k8s.gcr.io/kube-apiserver:v1.23.1 
docker pull k8s.gcr.io/kube-controller-manager:v1.23.1 
docker pull k8s.gcr.io/kube-scheduler:v1.23.1 
docker pull k8s.gcr.io/kube-proxy:v1.23.1 
docker pull k8s.gcr.io/pause:3.6 
docker pull k8s.gcr.io/etcd:3.5.1-0 
docker pull k8s.gcr.io/coredns/coredns:v1.8.6

If openEuler 20.03 or CentOS is used, you are advised to install Kubernetes 1.18.20.

          
               docker pull k8smx/kube-apiserver:v1.18.20
docker pull k8smx/kube-controller-manager:v1.18.20
docker pull k8smx/kube-scheduler:v1.18.20
docker pull k8smx/kube-proxy:v1.18.20
docker pull k8smx/pause:3.2
docker pull k8smx/coredns:1.6.7
docker pull k8smx/etcd:3.4.3-0

If you cannot pull images from dockerhub.io, you are advised to configure the Docker image accelerator in advance and use other image sources to download the required Docker images. For details about how to change the image source, see Changing the Image Source.

Query the Docker image components of Kubernetes.
```
docker images | grep k8s
```

Parent topic: Kubernetes Deployment Guide (CentOS & openEuler)