Flask App — AWS ECS Deployment

A minimal Flask web application built for learning containerization and deployment to AWS ECS (Elastic Container Service).

Part of the TrainWithShubham — DevOps Zero To Hero course.

Features

• Responsive landing page with modern glassmorphism UI
• /health endpoint for ECS load balancer health checks
• Two Dockerfiles — simple and multistage (distroless)

Tech Stack

Component	Technology
Framework	Flask 3.1.1
Runtime	Python 3.14
Container	Docker (python-slim / distroless)
Deploy	AWS ECS

Project Structure

flask-app-ecs/
├── app.py                 # Flask app with routes
├── run.py                 # Entry point (host 0.0.0.0, port 80)
├── requirements.txt       # Python dependencies
├── templates/
│   └── index.html         # Landing page
├── Dockerfile             # Simple single-stage build
└── Dockerfile-multi       # Multistage build with distroless

Quick Start

Run locally

pip install -r requirements.txt
python run.py

App runs at http://localhost:80.

Run with Docker

Simple build:

docker build -t flask-app .
docker run -p 80:80 flask-app

Multistage build (smaller, production-grade):

docker build -f Dockerfile-multi -t flask-app .
docker run -p 80:80 flask-app

Dockerfiles Explained

Simple (Dockerfile)

Single-stage build using python:3.14-slim. Straightforward — copies everything, installs dependencies, runs the app. Good for development and learning.

Multistage (Dockerfile-multi)

Two-stage build:

1. Builder stage — installs dependencies into a separate directory using python:3.14-slim
2. Final stage — copies only the app and deps into a distroless image

Benefits:

• Smaller final image (no pip, no shell, no OS utilities)
• Reduced attack surface — distroless images contain only the app and its runtime
• Better layer caching — dependencies are copied before source code

Endpoints

Route	Method	Description
/	GET	Landing page
/health	GET	Health check (returns Server is up and running)

Deploy to AWS ECS

High-level steps to deploy this app on ECS:

1. Push image to ECR

   aws ecr get-login-password --region <region> | docker login --username AWS --password-stdin <account-id>.dkr.ecr.<region>.amazonaws.com
   docker tag flask-app:latest <account-id>.dkr.ecr.<region>.amazonaws.com/flask-app:latest
   docker push <account-id>.dkr.ecr.<region>.amazonaws.com/flask-app:latest

2. Create ECS Task Definition — specify the ECR image, port 80, memory/CPU limits

3. Create ECS Service — attach to a cluster, configure desired count, link to a load balancer

4. Configure ALB — target group pointing to port 80, use /health as the health check path