“This is the sixth day of my participation in the First Challenge 2022. For details: First Challenge 2022”

Kubeadm is a K8s deployment tool that provides Kubeadm Init and Kubeadm Join for rapid deployment of Kubernetes clusters. The official address: kubernetes. IO/docs/refere…

The tool can deploy a Kubernetes cluster with two instructions:

1) create a Master node kubeadm init

$kubeadm join <Master Node IP address and port >

One, installation requirements

  • One or more machines, operating system Centos 7.X-86_X64
  • Hardware: 2GB or more RAM, 2 oR more cpus, 30GB or more hard disk
  • All the machines in the cluster are communicating properly
  • You can access the Internet. You need to pull the mirror
  • Disabling swap partitions

Two, prepare the environment

2.1 Three VMS

role ip hostname
master 192.168.184.137 k8s-master
worker node 192.168.184.138 k8s-node1
worker node 192.168.184.139 k8s-node2

2.2 Linux Initialization

2.2.1 Disabling the Firewall
systemctl stop firewalld
systemctl disable firewalld
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2.2.2 closed selinux
# permanent sed -i 's/enforcing/disabled/' /etc/selinux/config # temporary setenforce 0Copy the code
Then close the swap

A swap partition is a swap partition, or virtual memory on Windows. When the physical memory is insufficient, the operating system moves some of the temporarily unused data from the physical memory to the swap partition, thus leaving enough physical memory space for the currently running programs.

Kubelet made it mandatory for swap to be closed after version 1.8.

Temporary closure:

swapoff -a 
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Permanently close the following file and comment out the swap line

vi /etc/fstab
#/dev/mapper/centos-swap swap swap defaults 0 0
#Permanently shut down and restart Linux
reboot
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2.2.4 Setting the Host Name

The host names of the three VMS are as follows:

 hostnamectl set-hostname <hostname>
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2.2.5 Modifying hosts on the Master node
vi /etc/hosts
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Add the following:

192.168.184.137k8S-master 192.168.184.138k8S-node1 192.168.184.139k8S-node2Copy the code
2.2.6 Transferring bridge ipv4 Traffic to Iptables
echo "1" >/proc/sys/net/bridge/bridge-nf-call-iptables
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2.2.7 Synchronizing time
yum install ntpdate -y
ntpdate time.windows.com
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2.3 installation Docker/kubeadm/kubelet

Install Docker/kubeadm/kubelet among the three nodes

2.3.1 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 El7 systemctl enable docker && Systemctl start docker docker --versionCopy the code

Set ali source for Docker

vi /etc/docker/daemon.json
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Add the following:

{
"registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"]
}
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2.3.2 Adding the YUM Source
vi /etc/yum.repos.d/kubernetes.repo
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Add the following:

[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
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2.3.3 Installing kubeadm, kubelet and kubectl
Yum install -y kubelet-1.18.1-0 kubeadm-1.18.1-0 kubectl-1.18.1-0 systemctl enable kubelet-1.18.1-0Copy the code

3. Deploy nodes

3.1 Deploying a Master Node

3.1.1 Initializing kubeadm

Run the following command on 192.168.184.137:

Kubeadm init \ --apiserver-advertise-address=192.168.184.137 \ --image-repository Registry.aliyuncs.com/google_containers \ - kubernetes - version v1.18.1 \ - service - cidr = 10.96.0.0/12 \ - pod - network - cidr = 10.244.0.0/16Copy the code

The result is as follows:

. . Your Kubernetes control-plane has initialized successfully! To start using your cluster, you need to run the following as a regular user: mkdir -p $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config You should now deploy a pod network to the cluster. Run "kubectl apply -f [podnetwork].yaml" with one  of the options listed at: https://kubernetes.io/docs/concepts/cluster-administration/addons/ Then you can join any number of worker nodes by running the following on each as root: Kubeadm join 192.168.184.137:6443 --token cple2x.gieng4q082nrc2ml \ --discovery-token-ca-cert-hash sha256:5bd8349e530333725f7b70f6bce716156f81c337fc9cbb9eed9a68f11436375dCopy the code

3.1.2 kubectl tools

Next, using the Kubectl tool, execute the following commands respectively:

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
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View nodes:

NAME STATUS ROLES AGE VERSION K8S-Master NotReady Control-plane, Master 50S V1.21.1Copy the code

3.1.3 Installing a POD Network Plug-in (CNI)

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
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3.2 Adding a K8S Node

After executing kubeadm init, the command to add a node is printed:

Kubeadm join 192.168.184.137:6443 --token gr4zvu.05mcKhlvhve1rrvq -- discovery-tok-ca-cert-hash sha256:e9bc42fe3b0b6c991b7cb4489a319d8367f862b1034780cf1e0fca81909ef2ecCopy the code

If it is not recorded, run the following command to view it:

kubeadm token create --print-join-command
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If any of the following problems occur, you can use the kubeadm reset command to reset:

[preflight] Running pre-flight checks [WARNING Hostname]: hostname "k8s-node1" could not be reached [WARNING Hostname]: Hostname "k8S-node1 ": lookup k8s-node1 on 192.168.184.2:53: no such host error Execution phase preflight: [preflight] Some fatal errors occurred: [ERROR FileAvailable--etc-kubernetes-kubelet.conf]: /etc/kubernetes/kubelet.conf already exists [ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists [preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=... `Copy the code

4. Cluster verification

Create a pod in the Kubernetes cluster and verify that it is working properly by executing the following commands:

kubectl create deployment nginx --image=nginx
kubectl expose deployment nginx --port=80 --type=NodePort
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To view:

[root@k8s-master ~]# kubectl get pod,svc NAME READY STATUS RESTARTS AGE pod/nginx-6799fc88d8-zx89s 1/1 Running 0 27m NAME TYPE cluster-ip external-ip PORT(S) AGE service/kubernetes ClusterIP 10.96.0.1 < None > 443/TCP 143m service/nginx NodePort 10.111.56.177 < None > 80:30880/TCP 27mCopy the code

Respectively through three nodes access nginx, get the following interface: http://192.168.184.137:30880 http://192.168.184.138:30880 http://192.168.184.139:30880