Creating multi-node and multi-cloud Kubernetes cluster

Kubernetes:

Kubernetes, also known as K8s, is an open-source system for automating deployment, scaling, and management of containerized applications.

Amazon Web Service :

We can define AWS (Amazon Web Services) as a secured cloud services platform that offers compute power, database storage, content delivery, and various other functionalities. To be more specific, it is a large bundle of cloud-based services.

Microsoft Azure

Azure is a public cloud computing platform — ith solutions including Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) that can be used for services such as analytics, virtual computing, storage, networking, and much more. It can be used to replace or supplement your on-premise servers.

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Let’s start..

In this article, we are going to configure the Kubernetes multi-node cluster. Where we have configured the master in AWS, One slave in AWS, One slave in Microsoft azure, Two slaves in Local virtual instance.

• First, launch two basic EC-2 instances in AWS one for master and one for slave.

• Launch one vm on Azure to configure as slave of k8s cluster

• One Local VM is required to make slave of k8s cluster.

Open the Linux terminal, Now we are going the configure the Kubernetes master.

Kubernetes uses container technology, Therefore we are installing docker.

yum install docker -y

Now, start and enable the docker service.

systemctl start docker
systemctl enable docker

Changing the docker driver from cgroupfs to systems:

vim /etc/docker/daemon.json {
 "exec-opts": ["native.cgroupdriver=systemd"]
}

To apply this driver we need to restart the docker service

systemctl restart docker

To install Kubernetes into the system first we need to configure the k8s repository.

vim /etc/yum.repos.d/k8s.repo [kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-\$basearch
enabled=1
gpgcheck=1
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

Installing the required packages to run the master node

kubeadm — Kubeadm is a tool built to provide kubeadm init and kubeadm join as best-practice “fast paths” for creating Kubernetes clusters.

kubectl — You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs

kubelet — The kubelet is the primary “node agent” that runs on each node. It can register the node with the apiserver using one of the hostnames.

yum install kubeadm kubectl kubelet -y

Starting and enabling the kubelet service.

systemctl enable --now kubelet

To set up the Kubernetes cluster. We need to pull docker images using kubeadm. It pulls images of the config files.

kubeadm config images pull

Installing “iproute-tc” which will help us to manage the traffic on the cluster

yum install iproute-tc -y

Now, lets change IP tables /etc/sysctl.d/k8s.conf

vim /etc/sysctl.f/k8s.conf 
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1

The important step: Initializing Master

kubeadm init --control-plane-endpoint "PUBLICIP:PORT" --pod-network-cidr=10.244.0.0/16 --ignore-preflight-errors=NumCPU --ignore-preflight-errors=Mem

pod-network-cidr= IP range for pods inside the slave nodes

Control plane endpoint = assign the cluster with a public IP with port

ignore-preflight-errors= Ignoring the unwanted CPU errors and memory errors

Now the master is initialized.

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

Run the above commands.

To connect the nodes of the master and slave we use a flannel. Flannels act as a DHCP server as well as a router in the cluster. It will create a nating between the pods running in the cluster. The flannel works on the underlying network.

kubectl apply -fhttps://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

The above command will download and apply the flannel.

Generating Token:

The token is created at the time of initializing the master

kubeadm token create --print-join-command

This will print the token which we have to run on the slaves.

Now, The master is ready.

🔰 Slaves Configuration:

We are going the launch one slave in AWS, Second in Azure, third and fourth in local systems.

Perform all the below mentioned steps in all of those slave.

yum install iproute-tc    #Installing iproute-tc
yum install docker -y  #Install Docker 
vim /etc/docker/daemon.json     #Changing the driver
{
      "exec-opts": ["native.cgroupdriver=systemd"]
}
systemctl restart docker  #Restart docker
systemctl enable --now docker #enable Docker
#Kubernetes Repository
vim /etc/yum.repos.d/k8s.repo  [kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-\$basearch
enabled=1
gpgcheck=1
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
#Installing the required packages
yum install kubeadm kubectl kubelet -y
#Enabling kubelet service
systemctl enable --now kubelet
 
#Configure the iptables /etc/sysctl.d/k8s.confvim /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
sysctl --system

The above command I explained in detail while creating the master, they have the same meaning as in the master.

First, let’s connect the local systems.

Disable swap in the local systems

→ swapoff -a

Now, go to the master and print the token using the join command.

kubeadm token create --print-join-command

Copy the above-printed token and run it on all the slaves

Check the nodes using

kubectl get nodes

• output of above command

One slave is connected through AWS, master.lw.example.com and mlops-node are from the local systems.

In the azure instance the inbound and outbound rule are as follow:

Successfully created multi-node and multi-cloud Kubernetes cluster.

Thank you for visiting my article.