Greetings Application

This application is a simple REST-API service that responds with different salutations for customers. This code implements a Flask app that has liveness and readiness endpoints in addition to the / endpoint. Wich will serve customer A, B, or C based on os enviroment passed to the application. The liveness and readiness endpoints can be used to check if the app is healthy and ready to handle requests.

cdk8s is a tool that I used for writing Kubernetes manifests using familiar programming concepts. With cdk8s, you can define your application infrastructure using Python classes and methods, instead of writing raw YAML manifests.

Prerequisites

Python3
pip
cdk8s
cdk8s_plus_25

Manually Deployment

Install python virtual environment

sudo apt-get install python3-venv

Create a virtual environment and activate it

python3 -m venv .venv
source .venv/bin/activate

Install the required dependencies

pip install -r requirements.txt

Run the tests

python -m unittest greetings_test.py

Start the application per Customer

export CUSTOMER=A
flask --app greetings.py run

Test the API by sending a GET request to the endpoint for each customer

curl -s localhost:5000
"Hi"

Automated Deployment

You can use the provided pipeline script to build, test, lint, and deploy the application in one command

chmod +x ./pipeline.sh
./pipeline.sh

or using Makefile to run targeted tasks

make all

This script will:

Run the tests
Build the Docker image
Push the image to a container registry
Deploy the application to a Kubernetes cluster

Get confirmation that the application succesfully deployed on k8s cluster, IP_ADDRESS is loadbalancer ip or ingress controler ip.

curl -k --header 'Host: a.lab.io' https://IP_ADDRESS/
curl -k --header 'Host: b.lab.io' https://IP_ADDRESS/
curl -k --header 'Host: c.lab.io' https://IP_ADDRESS/

Testing HPA Autoscalling

hey -n 100000 -c 200 -q 10000 https://a.lab.io

Monitor hpa autoscalling changes

watch -n0.1 kubectl get hpa -n a-greetings-c82e96a1

To use cdk8s to make some changes

install cdk8s from documentation
navigate to manifest/cdk8s
do some changes
run

cdk8s synth

The output will be found in dist directory.

Conclusion

By following this guide, you should now have a working deployment of your Greetings application. You can use this pipeline to automatically deploy new versions of your application as you make changes and push them to the repository.

abdo-farag / greetings