# Kubernetes K8s Setup on CentOS:7 with easy steps.
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Taking inspiration from and dedicated to our training guru, Shri Maninder sir.
Hey everyone! In this article, we'll learn how to set up a Kubernetes (k8s) cluster on a Linux CentOS 7 machine. You can do this either on cloud servers or virtual machines within your infrastructure. If you are trying to set up a Kubernetes (k8s) cluster on an Ubuntu machine, try this [article link](https://rakeshkumarjangid.hashnode.dev/how-to-setup-kubernetes-cluster-over-cloud-on-ubuntu-os): [`https://rakeshkumarjangid.hashnode.dev/how-to-setup-kubernetes-cluster-over-cloud-on-ubuntu-os`](https://rakeshkumarjangid.hashnode.dev/how-to-setup-kubernetes-cluster-over-cloud-on-ubuntu-os), So let's start... --- ## **k8s Setting up on-premise virtual machines OR Cloud AWS Ec2 Instances.** | Cluster Type | Specifications | OS Type | | --- | --- | --- | | On-Primise VM (1 Master + 2 Worker) | 4 GRB RAM, 2 Core, 20 GB storage in each machine | Centos:7 | | Cloud AWS | T2.Medium or up | AWS Linux | --- ### Step 1: Check your IP or create a network using `#nmcli`
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Note: This Step-1 is only for On-Primise VMs, not for cloud AWS instances. and execute this step-1 on all cluster nodes including the master node .
```plaintext # cat /etc/os-release # nmcli con show NAME UUID TYPE DEVICE ens160 4443b0e3-1b19-3b0e-9861-7f0fbf825f6c ethernet ens160 ``` | ***VMs Nodes-Private-IP*** | VMs Node-Hostname | | --- | --- | | 192.168.1.1 | master.localhost.com | | 192.168.1.2 | w1.localhost.com | | 192.168.1.3 | w2.localhost.com | ```plaintext # hostnamectl set-hostname master.localhost.com && exec bash # nmcli con mod ens160 ipv4.addresses 192.168.1.1/24 ipv4.gateway 192.168.1.255 ipv4.dns 8.8.8.8 # nmcli con up ens160 ```
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Note: In the shortcut edit /etc/sysconfig/network-scripts/ifcfg-ensp*** file.
```plaintext # vi /etc/sysconfig/network-scripts/ifcfg-ensp*** IPADDR= ? NETMASK= ? GATEWAY=? DNS1=? ``` * Mention the hostname and IP address in the `/etc/hosts` file ```plaintext # vi /etc/hosts 192.168.1.1 www.master.localhost.com 192.168.1.2 www.w1.localhost.com 192.168.1.3 www.w2.localhost.com :wq! ``` --- ### Step 2: Disable swap memory, selinux & firewall ```plaintext # swapoff -a # sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab # setenforce 0 # sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config # systemctl disable firewalld && systemctl stop firewalld # free -h # sestatus # systemctl statuts firewalld ``` --- ### Step 3: Accessing SSH without using a password by sharing our public key.
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NOTE: Only From the master node, we'll generate a public key and then share it with the other worker nodes.
```plaintext # ssh-keygen -t rsa # ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.1.X ``` --- ### Step 4: Install Docker-CE Engine (Execute on all master + slave nodes both) ```plaintext # yum-config-manager --add-repo https://download.docker.com/linux/centos/dockerce.repo # yum install -y yum-utils device-mapper-persistent-data lvm2 # yum install docker-ce-20* -y # systemctl start docker && systemctl enable docker ``` --- ### Step 5: To update or add kernel arguments for both infra environments, and enable the bridge for all nodes including master. ```plaintext # cat < /etc/sysctl.d/k8s.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF ``` ```plaintext # sysctl --system ``` --- ### Step 6: Add Kubernetes Yum Repo from Google
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Note: Execute on all cluster nodes including the master node
```plaintext # cat <
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Note: Execute on all cluster nodes including master node
```plaintext # systemctl restart kubelet ; systemctl enable kubelet ; systemctl status kubelet ``` --- ### Step 9: Start Docker Host, containerd services (On all nodes including master) ```plaintext # systemctl enable docker && systemctl restart docker ``` --- ### Step 10: Initialize kubeadm init command `(On Master Node only)` ```plaintext # kubeadm init ```
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We will join the Worker node with the Master Node inside the Cluster in the future, so keep the output safe.
```plaintext # echo "kubeadm join 172.31.4.165:6443 --token kw9d4k.l44fcziztb3br21a \ --discovery-token-ca-cert-hash sha256:2952821ac60c0ddb079cc82bd621a72e61aae08a4e700c4f8d457058d7f51dd7" > ~/join.txt ``` --- ### Step 11: Start cluster configuration at `MASTER NODE Only` with regular user. ```plaintext $ mkdir -p $HOME/.kube $ cp -i /etc/kubernetes/admin.conf $HOME/.kube/config $ chown $(id -u):$(id -g) $HOME/.kube/config ``` --- ### Step 12: Download CNI Weave net `(Execute only on Master Node)` → ( Treated as Router)
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Official weave net link: <Official web page link>
```plaintext $ https://github.com/weaveworks/weave/releases/download/v2.8.1/weave-daemonset-k8s.yaml ``` --- ### Step 13: Go to the output of Step 10 and find the <`kubeadm join>` code and copy it at each worker node. ```plaintext # kubeadm join 172.31.4.165:6443 --token kw9d4k.l44fcziztb3br21a \ --discovery-token-ca-cert-hash sha256:2952821ac60c0ddb079cc82bd621a72e61aae08a4e700c4f8d457058d7f51dd7 ```
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Tip: If we forget join/hash code then we can run the following command :
```plaintext # kubeadm token create --print-join-command ``` --- ### Step-14: Check the connected cluster status at the Master Node ```plaintext $ kubectl get nodes -o wide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME master.localhost.com Ready master 1d 1.27.2 192.168.1.1 CentOS Linux 7 (Core) 4.19.0-19-amd64 docker://20.10.7 w1.localhost.com Ready 1d 1.27.2 192.168.1.2 CentOS Linux 7 (Core) 4.19.0-19-amd64 docker://20.10.7 w2.localhost.com Ready 1d 1.27.2 192.168.1.3 CentOS Linux 7 (Core) 4.19.0-19-amd64 docker://20.10.7 ``` ```plaintext $ kubectl get ns $ kubectl get pods -n kube-system -o wide $ kubect api-resources $ kubectl get po -n kube-system -o wide ``` --- Congratulations to all. Thanks you sir