Fullstack Python: Containerizing Flask Apps and Deploying on AWS ECS

In modern software development, containerization is revolutionizing how we build, ship, and deploy applications. For fullstack Python developers, using Docker to containerize a Flask app and deploying it via Amazon ECS (Elastic Container Service) unlocks a powerful, scalable, and production-ready workflow. This blog will guide you through containerizing your Flask app and deploying it to AWS ECS with simplicity and clarity.


Why Containerize Your Flask App?

A container is a lightweight, standalone executable that includes everything needed to run your application—code, runtime, libraries, and environment variables. Here’s why containers are ideal for deployment:

Consistency: Run your app the same way in development, testing, and production.

Portability: Containers can run on any system that supports Docker.

Scalability: Easily scale your app with container orchestration services like ECS or Kubernetes.

Isolation: Each container runs in its own isolated environment.


Step 1: Containerize Your Flask App with Docker

Let’s assume your Flask app has a basic structure:


bash


/flask-app

├── app.py

├── requirements.txt

└── Dockerfile

Create requirements.txt

bash

Copy

Edit

flask

gunicorn

Create a Dockerfile

Dockerfile

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Edit

# Use Python base image

FROM python:3.10-slim


# Set working directory

WORKDIR /app


# Copy files

COPY . /app


# Install dependencies

RUN pip install -r requirements.txt


# Expose port

EXPOSE 5000


# Run the app with Gunicorn

CMD ["gunicorn", "-b", "0.0.0.0:5000", "app:app"]

Build and Test Locally

bash

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Edit

docker build -t flask-app .

docker run -p 5000:5000 flask-app


Step 2: Push Docker Image to Amazon ECR (Elastic Container Registry)

Create a Repository

Go to AWS ECR.


Create a private repository named flask-app.


Authenticate Docker to ECR

bash

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Edit

aws ecr get-login-password --region <your-region> | \

docker login --username AWS --password-stdin <your-account-id>.dkr.ecr.<your-region>.amazonaws.com

Tag and Push Image

bash

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docker tag flask-app:latest <your-ecr-repo-uri>:latest

docker push <your-ecr-repo-uri>:latest


Step 3: Deploy on AWS ECS (Fargate)

Create a Cluster

Go to ECS > Clusters.

Choose “Networking only” for Fargate.

Name your cluster and create.

Create a Task Definition

Launch type: Fargate

Container name: flask-app

Image URI: Use the ECR image you pushed

Port mapping: 5000 (container) → 80 (load balancer)


Create a Service

Choose your task definition

Select number of tasks (e.g., 1)

Attach a load balancer (optional but recommended)

Define security groups and networking


Step 4: Access Your App

Once the ECS service is running, the load balancer (or public IP of the task) will provide access to your Flask app. Visit the URL in your browser and you’ll see your app live!


Final Thoughts

Deploying Flask applications on AWS ECS with Docker may seem intimidating at first, but it's one of the most powerful and scalable solutions for cloud-native applications. It allows you to manage infrastructure efficiently, roll out updates seamlessly, and handle scaling automatically.

With this containerized workflow, your Flask app becomes cloud-ready, resilient, and production-grade—ideal for fullstack developers aiming to build and deploy applications the modern way.


Learn FullStack Python Training

Read More : Fullstack Flask: Deploying Flask Apps on AWS EC2

Read More : Fullstack Python: Using Prometheus and Grafana for Microservices Monitoring

Read More : Fullstack Flask: Scaling Microservices with Kubernetes Horizontal Pod Autoscaling


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