install kubernetes on centos 7 with kubespray

What is k8s?

Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available

The name Kubernetes originates from Greek, meaning helmsman or pilot. K8s as an abbreviation results from counting the eight letters between the “K” and the “s”. Google open-sourced the Kubernetes project in 2014.

There are many different ways to install k8s. some of them are below:

1. Kops
2. KRIB
3. Kubeadm
4. Kubespray

In this post we are going to setup k8s cluster with kubespray

What is kubespray?

It’s a new way to install kubernetes cluster.Its is a combination of Ansible and kubernetes . This means we can install kubernetes using Ansible .

Kubespray is a project that contains a bunch of ansible playbooks which deploy kubernetes clusters in an automated way. It is very suitable installation, configuration and maintaining method for on-premise environments since you can use it to deploy kubernetes clusters on different linux distros like, Ubuntu, Coreos and Centos.

Benefits of using kubespray?

• Kubespray provides deployment flexibility. It allows you to deploy a cluster quickly and customize all aspects of the implementation.
• Kubespray strikes a balance between flexibility and ease of use.
• You only need to run one Ansible playbook and your cluster ready to serve.

Lets Start…….

In this post I am setting up 3 node cluster

Requirement

Here I am installing three node clusters which include one master node and two worker node. And make sure that password less authentication is enabled between the servers

Steps:-

1. Disable SElinux
2. Install Packages(git, epel-release, python)
3. Clone kubespray repo and Install requirements
4. Generate ssh key for password less authentication.
5. Update the ansible inventory file.
6. Now lets Deploy cluster with ansible

Step 1:- Disable SElinux

Here disable SElinux on all nodes

Preparing ansible

setenforce 0
sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux
systemctl disable firewalld; systemctl stop firewalld; systemctl mask firewalld

Setp 2:- Install Packages(git, epel-release, python)

Install these packages on Ansible node (from where you are going to execute our ansible playbook)

yum update -y
yum install git -y
yum install epel-release -y
yum install python-pip -y
pip install --upgrade pip 

Step 3:- Clone Kubespray repo and Install requirements.

• clone Kubespray repo

git clone https://github.com/kubernetes-sigs/kubespray.git

• Install Requirements

cd kubespray
pip install -r requirements.txt

If you face below error while installing requirements.txt

then follow below steps:-

wget https://bootstrap.pypa.io/pip/2.7/get-pip.py
python get-pip.py

• Copy inventory/sample as inventory/mycluster (change mycluster to any name you want for the cluster)

 cp -rfp inventory/sample inventory/cloudsbaba

Step 4:- Generate ssh key and placed over all the nodes

ssh-keygen -t rsa

Step 5:- Update the ansible inventory file

cd kubespray/inventory/cloudsbaba
cp inventory.ini hosts.ini

update the host.ini with your hosts like below

After adding host info check if all the servers are accessible via ansible or not

 ansible -i hosts.ini -m ping all

Step 6:- Now lets Deploy cluster with ansible

ansible-playbook -i inventory/cloudsbaba/hosts.ini cluster.yml --become -vvv

it will take 5-10 min to complete depending upon your network speed

lets check the status of the node

kubectl get nodes 

Here you can see the status of nodes

lets suppose you want to remove the node from the cluster

ansible-playbook -i inventory/cloudsbaba/hosts.ini remove-node.yml -e "node=worker-node1" --become -vvv

lets suppose you want to add node to cluster

Navigate to your hosts.ini file and add a nod entry as you added in step 5.

after that execute the below script

ansible-playbook -i inventory/cloudsbaba/hosts.ini scale.yml --become -vvv

Congratulations…. you follow all the steps and deploy k8s with kubespray

References:-

• https://kubernetes.io/docs/concepts
• https://www.redhat.com/sysadmin/kubespray-deploy-kubernetes
• https://github.com/kubernetes-sigs/kubespray