How to install Kubernetes Cluster on AWS EC2 instances

How to install Kubernetes Cluster on AWS EC2 instances


This is a guide for setting up a Kubernetes cluster over AWS EC2 instances from scratch. Let’s start with the prerequisites first.

Prerequisites:

  • You need to have created at least one AWS EC2 instance for acting as Master node and at least one AWS EC2 instance to act as a worker node.
  • In this tutorial, I have used Amazon Linux 2 AMI when I lunched EC2 instances, which is based on centos Linux. This AMI also has some pre-installed libraries that AWS does for you. However, you can use any centos-based system such as RHEL as well. In that case, most of the commands remain the same.
  • While launching AWS ec2 instances, make sure that you open all the ports in the related security groups.
  • Both the AWS EC2 instances need to be on the same VPC and preferably same availability zone.
  • Needless to say, you need to have putty/terminal to connect to your EC2 instances.

Connect to both the ec2 instances using two putty terminals. Decide which EC2 instance would be the master/manager and which would be worker/slave. Henceforward we will call them master and worker nodes. There are a few commands that we need to run on the master as well as the worker node.

Hope you are ready with all that is written in the prerequisites.

Ports for the Control-plane (Master) Node(s)

Ports for the Worker Node(s)


On both the master and worker nodes:

Be a root user. Install Docker and start Docker service. Also, enable the docker service so that the docker service starts on system restarts.

sudo su
yum install docker -y 
systemctl enable docker && systemctl start docker

Create proper yum repo files so that we can use yum commands to install the components of Kubernetes.

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]

name=Kubernetes

baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64

enabled=1

gpgcheck=1

repo_gpgcheck=0

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

exclude=kube*

EOF

sysctl command is used to modify kernel parameters at runtime. Kubernetes needs to have access to kernel’s IP6 table and so we need to do some more modifications. This includes disabling secure Linux.

cat <<EOF >  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sysctl --system
setenforce 0

Install kubelet, kubeadm and kubectl; start kubelet daemon

yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
systemctl enable kubelet && systemctl start kubele

Only on the Master Node:

On the master node initialize the cluster.

ifconfig 
(copy the internet ip and give it as per your cidr)
sudo kubeadm init --pod-network-cidr=192.168.0.0/16 --ignore-preflight-errors=NumCPU
sudo kubeadm init --pod-network-cidr=192.168.0.0/16 #Do this only if proper CPU cores are available

Wait for around 4 minutes. Following commands will appear on the output screen of the master node. Either copy and paste that in the same terminal or copy it from here and apply it on the master’s terminal.

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

This will also generate a kubeadm join command with some tokens.

On Worker nodes:

After initializing the cluster on the master node. copy kubeadm join command from output of kubeadm init on master node. (Switch to the root mode first)

sudo su
<kubeadm join command copies from master node>

On the master node as well as the worker node initialize KUBECONFIG so that kubectl commands can be executed.

export KUBECONFIG=/etc/kubernetes/kubelet.conf

Now our cluster is created, you can see these by using the command below:

kubectl get nodes

The output of the command above will show both the nodes in NOTREADY state. That is because Kubernetes needs an “overlay network” so that pod-to-pod communication can happen properly. This overlay network is created by third-party CNI plugins. We are going to use Calico to create that overlay network.

Create an Overlay network using Calico CNI plugin on Master node

For calico networking copy-paste these commands and apply on the master node only

sudo kubectl apply -f https://docs.projectcalico.org/v3.2/getting-started/kubernetes/installation/hosted/etcd.yaml
sudo kubectl apply -f https://docs.projectcalico.org/v3.2/getting-started/kubernetes/installation/rbac.yaml
sudo kubectl apply -f https://docs.projectcalico.org/v3.2/getting-started/kubernetes/installation/hosted/calico.yaml

Take a pause of 2 minutes and see if the nodes are ready; run it on master node

kubectl get nodes

You should be able to see the list of two nodes and both should be in READY state.

Watch all the system pods.

kubectl get pods --all-namespaces

You should be able to see a lot of pods in the output of above command. If it is not working, try reloading the root profile by running the command below and try hitting the previous command.

sudo su –
kubectl get pods --all-namespaces

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