How to Install Kubernetes Cluster on CentOS 7

Install Kubernetes Cluster on CentOS 7

1. Update the packages

 yum update

2. ==== Install the dependencies
   yum install -y yum-utils device-mapper-persistent-data lvm2

3. Add and enable official Docker Repository to CentOS 7

 sudo-yum-config-manager---add-repo-httpsdownload.docker.comlinuxcentosdocker-ce.repo
 sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo 

4. ==== Install the latest Docker version on CentOS 7
   yum install docker-ce
5. ==== Start and enable the docker
   
   systemctl start docker

 systemctl enable docker 

6. ==== Confirm that Docker is active
   systemctl status docker
7. === Set up the Kubernetes Repository
   vi /etc/yum.repos.d/kubernetes.repo ============
   
   [kubernetes] ===

repo_gpgcheck=1

=== gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

==========

8. === Install Kubelet on CentOS 7
   yum install -y kubelet ===
9. === Install kubeadm and kubectl on CentOS 7
   yum install -y ===
10. === Set hostnames
    hostnamectl set-hostname W-node1 sudo exec bash
    Repeat the same steps on worker-node
    ===

11. Add nodes in the master kubernetes server

$ vi /etc/hosts

======
IP master-node
IP node1 <hostname of worker node>

12. === Disable SElinux
    
    $ sudo setenforce 0
    $ sudo sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux
    $ reboot
    ===
13. === Add firewall rules
    
    sudo firewall-cmd --permanent --add-port=6443/tcp ===

 sudo firewall-cmd --permanent --add-port=2379-2380/tcp 

 sudo firewall-cmd --permanent --add-port=10250/tcp 

 sudo firewall-cmd --permanent --add-port=10251/tcp 

 sudo firewall-cmd --permanent --add-port=10252/tcp 

 sudo firewall-cmd --permanent --add-port=10255/tcp 

 sudo firewall-cmd –reload 

Note:

Need to add firewall rule on the worker -node as per the port configured

 sudo firewall-cmd --permanent --add-port=10251/tcp 

 sudo firewall-cmd --permanent --add-port=10255/tcp 

 sudo firewall-cmd –reload 

=== Update iptables config

 vi /etc/sysctl.d/k8s.conf

===========

net.bridge.bridge-nf-call-ip6tables = 1 ===

=== net.bridge.bridge-nf-call-iptables = 1

========

$ sysctl --system ===

===

===

15. === Disable swap
    $ sudo sed -i '/swap/d' /etc/fstab
    $ sudo swapoff -a
    ===
16. === kubeadm initialization
    
    $ sudo kubeadm init
    Note:
    Save the token generated in safer place, else we can retrieve it from the below command
    
    ===

$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

===

===

$ kubectl get pods --all-namespaces

=== Note:

If we found master–node is NotReady,the CoreDNS service is also not running. To resolve this execute the below command

$ sudo export kubever=$(kubectl version | base64 | tr -d '\n') ===

=== $ sudo kubectl apply -f https://cloud.weave.works/k8s/net?k8s-version=$kubever

Then check the node status to confirm the master node is running or not

$ kubectl get nodes ===

=== Download the code from the production server to Kubernetes server and create a Dockerfile to create an image

$ vi Dockerfile

===

==========

1. Use the official Nginx image as the base image

FROM nginx:alpine

1. Copy the provided files to the Nginx document root

COPY . /usr/share/nginx/html/

1. Expose port 80 for HTTP

EXPOSE 80

1. Start Nginx when the container starts

CMD ["nginx", "-g", "daemon off;"]

=======

20. === Run the docker image
    $ docker build -t my-node-app .
    To list the docker image
    $ docker images
    ===
21. === Create a container form the docker image
    
    $ docker run -d -p 80:80 my-node-app
    
    To list the docker containers
    
    $ docker ps -a
    ===
22. === Login the docker hub
    
    $ docker login -u username
    
    Note: Provide the access token if the 2FA authentication has been enabled
    ===
23. === Push the image to the docker hub
    $ docker tag image-name your-docker-hub-username/repository-name:tag
    ===
24. === Repeat steps from 1 to 15 on the worker node
    Note: Replace the IP and hostname where it is required as per the worker node
    ===
25. === On the worker node, copy the token generated in the step 15 and replace the IP of the worker node and execute this command to add this to kubernetes cluster
    
    $ sudo kubeadm join <master-node-ip>:6443 --token <token> --discovery-token-ca-cert-hash <ca-cert-hash> ===

===
For example:
$ sudo kubeadm join 69.30.219.165:6443 --token edd9qs.5240fnpey1a4kctw --discovery-token-ca-cert-hash sha256:bd4ceb4caf0615872583d540248439a46c50d1d104da3704f597c0817c0d1458 ===

=== On the master node verify the nodes

$ kubectl get nodes

===

Deployment.yaml

apiVersion: apps/v1 kind: Deployment metadata: name: dsmterminal.milta.be spec: replicas: 1 selector: matchLabels: app: dsmterminal.milta.be template: metadata: labels: app: dsmterminal.milta.be spec: imagePullSecrets: - name: regcred containers: - name: dsmmilta-terminal-container image: pheonixsolutions/dsm-milta-terminal:latest ports: - containerPort: 80 # Adjust the port based on your application requirements

Ingress.yaml

apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: nginx-ingress annotations: spec: ingressClassName: nginx rules: - host: dsmterminal.milta.be http: paths: - pathType: Prefix path: "/" backend: service: name: nginx-ingress port: number: 80

=== Service.yaml file

===

apiVersion: v1 kind: Service metadata: name: dsmterminal labels: app: dsmterminal.milta.be spec: ports: - appProtocol: http name: http port: 80 protocol: TCP targetPort: 80 selector: app: dsmterminal.milta.be type: ClusterIP

1. kubectl apply -f service.yaml