Hackernoon logoHow To Install Kubernetes on CentOS7 by@jhooq

How To Install Kubernetes on CentOS7

This tutorial is for the ones who want to try out the Kubernetes installation on CentOS. It has been simplified the installation into 15 steps. The instructions are below: How To Instabut the instructions and instructions for installing VMs on CentOS 7.7 or latest – For installation instruction click here: Vagrant 2.2.7. VMs are two VMs – master, worker and virtual box – VMs with 2 CPU, 1 GB Memory (Assinged IP – 100.0.1) Master Node – 2 cpus, 2 GB Memory. Worker Node – 1 cpu, 1GB Memory. Master node – 1 CPU. Worker node.
Rahul Wagh Hacker Noon profile picture

@jhooqRahul Wagh


This tutorial is for the ones who want to try out the Kubernetes installation on CentOS.

In this article, I have simplified the installation into 15 steps for installing Kubernetes on CentOS “bento/centos-7”

Before you begin with installation here are prerequisites for installing Kubernetes on CentOS.


  • Reading time is about 20 minutes
  • Vagrant 2.2.7 or latest – For installation instruction click here
  • VM VirtualBox – For installation instruction click here

Step 1: Start your vagrant box

Use the following Vagrantfile to spin up your vagrant box.

We are going with two VMs here –

  1. Master Node – 2 cpus, 2 GB Memory (Assinged IP – )
  2. Worker Node – 1 cpu, 1 GB Memory (Assinged IP – )
  3. Vagrant.configure("2") do |config|
      config.vm.define "master" do |master|
        master.vm.box_download_insecure = true    
        master.vm.box = "bento/centos-7"
        master.vm.network "private_network", ip: ""
        master.vm.hostname = "master"
        master.vm.provider "virtualbox" do |v|
          v.name = "master"
          v.memory = 2048
          v.cpus = 2
      config.vm.define "worker" do |worker|
        worker.vm.box_download_insecure = true 
        worker.vm.box = "bento/centos-7"
        worker.vm.network "private_network", ip: ""
        worker.vm.hostname = "worker"
        worker.vm.provider "virtualbox" do |v|
          v.name = "worker"
          v.memory = 1024
          v.cpus = 1

Step 2: Update /etc/hosts on both nodes(master, worker)

master node – SSH into the master node

$ vagrant ssh master
[email protected]:~$ sudo vi /etc/hosts master.jhooq.com master worker.jhooq.com worker

worker node- SSH into the worker node

$ vagrant ssh worker
[email protected]:~$ sudo vi /etc/hosts master.jhooq.com master worker.jhooq.com worker

Test the worker node by sending ping from master

[[email protected] ~]$ ping worker
PING worker.jhooq.com ( 56(84) bytes of data.
64 bytes from worker.jhooq.com ( icmp_seq=1 ttl=64 time=0.462 ms
64 bytes from worker.jhooq.com ( icmp_seq=2 ttl=64 time=0.686 ms
Test the master node by sending ping from worker
[[email protected] ~]$ ping master
PING master.jhooq.com ( 56(84) bytes of data.
64 bytes from master.jhooq.com ( icmp_seq=1 ttl=64 time=0.238 ms
64 bytes from master.jhooq.com ( icmp_seq=2 ttl=64 time=0.510 ms

Step 3: Install Docker on both nodes (master, worker)

You need to install Docker on both the node

So run the following docker installation command on both the nodes

[[email protected] ~]$ sudo yum install docker -y

Enable docker: on both master and worker node

[[email protected] ~]$ sudo systemctl enable docker
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

Start docker: on both master and worker node

[[email protected] ~]$ sudo systemctl start  docker

Check the docker service status

[[email protected] ~]$ sudo systemctl status docker

Docker service should be up and running and you should get following output on the terminal

● docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2020-04-23 18:00:12 UTC; 26s ago
     Docs: http://docs.docker.com
 Main PID: 11892 (dockerd-current)

Step 4: Disable SELinux on both nodes(master, worker)

You need to disable the SELinux using following command

[[email protected] ~]$ sudo setenforce 0
[[email protected] ~]$ sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

Step 5: Disable CentOS firewall on both nodes(master, worker)

Master Node

[[email protected] ~]$ sudo systemctl disable firewalld
[[email protected] ~]$ sudo systemctl stop firewalld

Worker Node

[[email protected] ~]$ sudo systemctl disable firewalld
[[email protected] ~]$ sudo systemctl stop firewall

Step 6: Disable swapping on both nodes(master, worker)

Disable the swapping on master as well as a worker node. Because to install Kubernetes we need to disable the swapping on both the nodes

Run following command on both master as well as worker node

[[email protected] ~]$ sudo swapoff -a

Step 7: Enable the usage of “iptables” on both nodes(master, worker)

Enable the usage of iptables which will prevent the routing errors happening. As the following runtime parameters:

[[email protected] ~]$ sudo bash -c 'echo "net.bridge.bridge-nf-call-ip6tables = 1" > /etc/sysctl.d/k8s.conf'
[[email protected] ~]$ sudo bash -c 'echo "net.bridge.bridge-nf-call-iptables = 1" >> /etc/sysctl.d/k8s.conf'
[[email protected] ~]$ sudo sysctl --system

Step 8: Add the Kubernetes repo to rum.repos.d on both nodes(master, worker)

[[email protected] ~]$ sudo vi /etc/yum.repos.d/kubernetes.repo

Add following repo details –


Step 9: Install Kubernetes on both nodes(master, worker)

[[email protected] ~]$ sudo yum install -y kubeadm kubelet kubectl

Step 10: Enable and Start Kubelet on both nodes(master, worker)

Run the following command both on master and worker nodes.

Enable the kubelet

[[email protected] ~]$ sudo systemctl enable kubelet
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.

Start the kubelet

[[email protected] ~]$ sudo systemctl start kubelet

Step 11: Initialize Kubernetes cluster only on master node

Initialize the Kubernetes cluster (–apiserver-advertise-address= this is the IP address we have assigned in the /etc/hosts)

[[email protected] ~]$ sudo kubeadm init --apiserver-advertise-address= --pod-network-cidr=
Note down the kubeadm join command
kubeadm join --token cfvd1x.8h8kzx0u9vcn4trf \
    --discovery-token-ca-cert-hash sha256:cc9687b47f3a9bfa5b880dcf409eeaef05d25505f4c099732b65376b0e14458c

Step 12: Move kube config file to current user (only run on master)

To interact with the Kubernetes cluster and to use kubectl command, we need to have the Kube config file with us.

Use the following command to get the kube config file and put it under the working directory.

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

Step 13: Apply CNI from kube-flannel.yml(only run on master)

After the master of the cluster is ready to handle jobs and the services are running, for the purpose of making containers accessible to each other through networking, we need to set up the network for container communication.

Get the CNI(container network interface) configuration from flannel

[[email protected] ~]$ wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Note – But since we are working on the VMs so we need to check our Ethernet interfaces first.

Look out for the Ethernet i.e. eth1 which has a ip address is the ip address which we used in vagrant file)

[[email protected] ~]$ ip a s
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:bb:14:75 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:fb:48:77 brd ff:ff:ff:ff:ff:ff

Now we need to add the extra args for eth1 in kube-flannel.yml

[[email protected] ~]$ vi kube-flannel.yml

Searche for – “flanneld”

In the args section add : – –iface=eth1

- --iface=eth1
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=eth1

Apply the flannel configuration

[email protected]:~$ kubectl apply -f kube-flannel.yml
podsecuritypolicy.policy/psp.flannel.unprivileged created
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.apps/kube-flannel-ds-amd64 created
daemonset.apps/kube-flannel-ds-arm64 created
daemonset.apps/kube-flannel-ds-arm created
daemonset.apps/kube-flannel-ds-ppc64le created
daemonset.apps/kube-flannel-ds-s390x created

Step 14: Join master node run only on worker node

In the Step 11 we generated the token and kubeadm join command.

Now we need to use that join command from our worker node

[[email protected] ~]$ sudo kubeadm join --token cfvd1x.8h8kzx0u9vcn4trf --discovery-token-ca-cert-hash 
W0423 18:50:54.480382    8100 join.go:346] [preflight] WARNING: JoinControlPane.controlPlane settings will be ignored when control-plane flag is not set.
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Downloading configuration for the kubelet from the "kubelet-config-1.18" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

Step 15: Check the nodes status(only run on master)

Check the nodes status in the master

[[email protected] ~]$ kubectl get nodes
master   Ready    master   26m   v1.18.2
worker   Ready    <none>   63s   v1.18.2

For more similar kubernetes article please refer to - 14 Steps to Install kubernetes on Ubuntu

Previously published at https://jhooq.com/15-steps-to-install-kubernetes-on-bento-centos7


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