7 - Install Kubernetes - via kubeadm

Prerequisites:

Node	OS	IP
k8s-master	CentOS7	192.168.137.161
k8s-node1	CentOS7	192.168.137.162

 

 

 

 

We now have Docker running on both master and node1, it's time to provision Kubernetes on them. There are 3 ways to provision Kubenetes cluster: binary installation, kubeadm initialization, and minikube. We go with kubeadm.

Provision Kubernetes:

1. Installing kubeadm, kubelet and kubectl (On both master and node)

   kubeadm: the command to bootstrap the cluster.

   kubelet: the component that runs on all of the machines in your cluster and does things like starting pods and containers.

   kubectl: the command line util to talk to your cluster.
   Execute below command to get those 3 tools installed (Please specify tools version 1.21.1, as we will install k8s 1.21, otherwise you will encounter too many version conflict issues and it's hard to troubleshooting, believe me!):

   yum install -y kubelet-1.21.1 kubeadm-1.21.1 kubectl-1.21.1

    

2. Start kubelet and set as auto launch (On both master and node)
   

   systemctl enable kubelet && systemctl start kubelet

    You have now successfully installed Kubenetes with it's basic tools and packages

3. Deploy Kubernetes Master Node
   Run below command on Master terminal:
   

   kubeadm init \
   --apiserver-advertise-address=192.168.137.161 \
   --image-repository registry.aliyuncs.com/google_containers \
   --kubernetes-version v1.21.0 \
   --service-cidr=10.1.0.0/16 \
   --pod-network-cidr=10.244.0.0/16

    

   Note: you can find Kubernetes versions on official site https://kubernetes.io/
   If you facing below issue to pull coredns, then you need to pull coredns manually:
   
   Manually pull coredns:v1.8.0 (Since we install the latest version of K8S which has dependancy on coredns:v1.8.0 and Aliyun don't have it):
   

   docker pull coredns/coredns:1.8.0
   docker tag coredns/coredns:1.8.0 registry.aliyuncs.com/google_containers/coredns/coredns:v1.8.0
   docker rmi -f coredns/coredns:1.8.0

    And then run the previous kubeadm init command again, waiting the cluster initialize to complete:

   
   NOTE: If any issue encoutered during installation try to run below command, then execute the kubeadm init again
   swapoff -a && kubeadm reset  && systemctl daemon-reload && systemctl restart kubelet  && iptables -F && iptables -t nat -F && iptables -t mangle -F && iptables -X
4. Start cluster
   By following above console output, run below command to start our k8s cluster:
   

   [root@master01 ~]# mkdir -p $HOME/.kube
   [root@master01 ~]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
   [root@master01 ~]# sudo chown $(id -u):$(id -g) $HOME/.kube/config
   [root@master01 ~]# kubectl get nodes

   You will find the working node we have is just the master node, and it's showing status NotReady:
   

5. We have now running the master node, next let's introduce k8s network, to make our cluster READY, and adding node into it !