2 tier application deployment on kubernetes

What is Kubernetes?

Kubernetes is an open-source container orchestration tool for automating deployment, scaling and management of containerized applications.

It is also known as k8s.

So, let's proceed with the 2 tier application deployment on Kubernetes.

Prerequisites:

• Ubuntu OS (Xenial or later)

• sudo privileges

• Internet access

• t2.medium instance type or higher

Setup Kubeadm on AWS

Both the Master and Worker node

Run the following commands on both the master and worker nodes to prepare them for kubeadm.

# using 'sudo su' is not a good practice.
sudo apt update
sudo apt-get install -y apt-transport-https ca-certificates curl
sudo apt install docker.io -y

sudo systemctl enable --now docker # enable and start in single command.

# Adding GPG keys.
curl -fsSL "https://packages.cloud.google.com/apt/doc/apt-key.gpg" | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/kubernetes-archive-keyring.gpg

# Add the repository to the sourcelist.
echo 'deb https://packages.cloud.google.com/apt kubernetes-xenial main' | sudo tee /etc/apt/sources.list.d/kubernetes.list

sudo apt update 
sudo apt install kubeadm=1.20.0-00 kubectl=1.20.0-00 kubelet=1.20.0-00 -y

---

Master Node

1. Initialize the Kubernetes master node.

sudo kubeadm init

1. Set up local kubeconfig (both for the root user and normal user):

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

1. Apply Weave network:

kubectl apply -f https://github.com/weaveworks/weave/releases/download/v2.8.1/weave-daemonset-k8s.yaml

1. Generate a token for worker nodes to join:

sudo kubeadm token create --print-join-command

1. Expose port 6443 in the Security group for the Worker to connect to Master Node

---

Worker node

1. Run the following commands on the worker node

sudo kubeadm reset pre-flight checks

1. Paste the join command you got from the master node and append --v=5 at the end. Make sure either you are working as sudo user or use sudo before the command

2. After succesful join->

---

Verify cluster connection

on Master Node:

kubectl get nodes

If you get the output as ready, it means your kubeadm is successfully set up.

---

• Clone code on Master node

git clone <github_repo_url>

example:

git clone https://github.com/DevMadhup/two-tier-flask-app.git

• Move to the work directory to implement k8s deployment

cd two-tier-flask-app/k8s

• Execute the backend-deployment.yml file to run the application container.

kubectl apply -f backend-deployment.yml

• Execute the service file so that the application would be available to the outside world or users.

kubectl apply -f backend-deployment-svc.yml

• Expose database

kubectl apply -f mysql-deployment-svc.yml

• Execute mysql-deployment file to run the mysql container

Note: Make sure to edit mysql-deployment file and change the MYSQL_HOST variable

kubectl apply -f mysql-deployment.yml

• Persist the data of mysql attach the persistent volume to mysql container.

kubectl apply -f persistent-volume.yml

• After creating persistent volume, we have to claim the persistent volume

kubectl apply -f persistent-volume-claim.yml

At last, expose port 30004 on the security group of the Worker node and access your application on

http://<public_ip>:30004

Congratulations, you made it !!!!!!!

You have successfully deployed 2 tier flask application with MySQL database on Kubernetes.