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Kubernetes Installation With RKE

In this blog, we'll guide you through the seamless installation of a Kubernetes cluster on a RHEL-based operating system. Our setup involves two nodes; one serving as both the RKE and master node, and the other dedicated as a worker node.

Let's start with a step-by-step process, starting from creating virtual machines on the Alces Cloud platform, leading up to the installation of the Kubernetes cluster using RKE.

Launch the Instance

Launch 2 instances for our setup where one node will act as a rke and master node, whereas second node will act as worker node in the kubernetes cluster.

All the steps to launch and connection to instance is provided in link.

Kubernetes Installation with RKE

Here we have 2 types of nodes: rke node: node where rke utility is installed that is responsible for installation of k8s cluster on other nodes. k8s nodes: nodes that are the part of k8s cluster where installation takes place.

Prerequisites

  • Docker must be installed on all the nodes of k8s cluster. 

    sudo dnf check-update
sudo dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
sudo dnf install docker-ce docker-ce-cli containerd.io
sudo systemctl start docker
sudo systemctl status docker
sudo systemctl enable docker

# Execute docker cli without sudo
sudo usermod -aG docker $(whoami)

# You will need to log out of the Droplet and back in as the same user to enable this change.

  • password less ssh to all k8s nodes from rke node.

Here we are creating a cluster with one master node and one worker node, so number of vm required here is 2. we also need to setup a rke node as well.

Initial setup for RKE node

  • Install RKE On the first instance we will be installing rke cli to install our cluster, below are the instructions.

wget https://github.com/rancher/rke/releases/download/v1.2.9/rke_linux-amd64 -O rke chmod +x rke
- Perform a password-less ssh from rke node to k8s nodes. - Install kubectl to access k8s resources.

yum install epel-release
yum install snapd
systemctl enable --now snapd.socket
ln -s /var/lib/snapd/snap /snap
snap install kubectl --classic

Initial setup for k8s node

  1. Disabled selinux on all nodes and firewalld. 

    setenforce 0  
systemctl stop firewalld

  2. Install Docker on all nodes.

yum update –y 
yum install -y yum-utils  
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo 
yum install docker-ce docker-ce-cli containerd.io 
systemctl start docker  
systemctl enable docker

Steps for installation of K8s cluster

On the rke node, create a cluster.yml file specifying the user , ip of k8s nodes, type of networking , roles and version of k8s we want to install.

# cluster.yml
nodes: 
- address: 10.151.0.xx
  user: rke 
  role: 
    - controlplane 
    - etcd 
  hostname_override: master

- address: 10.151.0.xx
  user: rke 
  role: 
    - worker
  hostname_override: worker

kubernetes_version: v1.20.8-rancher1-1
network: 
    plugin: canal

  1. Then execute ./rke up Sometimes it will say that docker version is not supported, then execute ./rke up --ignore-docker-version.

  2. Once the installation is complete you will get a file named kube_config_cluster.yml in the same directory i.e. the kubeconfig of cluster we have created.