🚀 Building a CI/CD Pipeline with GitHub Actions, Docker, and AWS EC2

👋 Introduction

In this blog, I’ll walk you through how I built a complete CI/CD pipeline to deploy a Flask application using GitHub Actions, Docker, and AWS EC2.

This hands-on project gave me a deeper understanding of DevOps practices like automated builds, containerization, and remote deployment — all using free-tier AWS resources.

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🧰 Tech Stack Used

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🏗️ Step 1: Create a Simple Flask App

I started with a minimal Flask app.

app.py

from flask import Flask
app = Flask(__name__)

@app.route('/')
def home():
    return "Hello from Flask CI/CD on AWS!"

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000)

requirements.txt

flask

Test locally:

python3 app.py

Visit: http://localhost:5000

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🐳 Step 2: Dockerize the App

Dockerfile

FROM python:3.11-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
EXPOSE 5000
CMD ["python", "app.py"]

Build and run locally:

docker build -t flask-cicd .
docker run -p 5000:5000 flask-cicd

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📤 Step 3: Push Code to GitHub

I initialized a Git repo and pushed the code:

git init
git add .
git commit -m "Initial commit"
git remote add origin https://github.com/mahesh-diwan/flask-cicd.git
git push -u origin master

🔗 View Repo on GitHub

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☁️ Step 4: Push Docker Image to Docker Hub

docker tag flask-cicd maheshdiwan/flask-cicd:latest
docker push maheshdiwan/flask-cicd:latest

🔗 Docker Hub Image

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🔁 Step 5: GitHub Actions CI/CD Workflow

This GitHub Actions workflow automates:

• Docker build on every push

• Docker push to Docker Hub

• SSH into EC2 and run the container

.github/workflows/deploy.yml

name: Build and Deploy

on:
  push:
    branches: [master]

jobs:
  build-and-deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - uses: docker/setup-buildx-action@v3

      - uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Build and Push Docker image
        run: |
          docker build -t ${{ secrets.DOCKER_USERNAME }}/flask-cicd:latest .
          docker push ${{ secrets.DOCKER_USERNAME }}/flask-cicd:latest

      - name: Deploy to EC2 via SSH
        uses: appleboy/ssh-action@v0.1.7
        with:
          host: ${{ secrets.EC2_HOST }}
          username: ubuntu
          key: ${{ secrets.EC2_SSH_KEY }}
          script: |
            docker pull ${{ secrets.DOCKER_USERNAME }}/flask-cicd:latest
            docker stop flask-cicd || true
            docker rm flask-cicd || true
            docker run -d --name flask-cicd -p 5000:5000 ${{ secrets.DOCKER_USERNAME }}/flask-cicd:latest

✅ Secrets are configured in the GitHub repo:

• DOCKER_USERNAME

• DOCKER_PASSWORD

• EC2_HOST

• EC2_SSH_KEY

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🖥️ Step 6: Set Up EC2 on AWS

I launched a t2.micro Ubuntu EC2 instance, then:

• Installed Docker:

sudo apt update
sudo apt install docker.io -y

• Opened ports 22 and 5000 in the security group

• Added my private SSH key to GitHub Secrets

• Pushed to GitHub to trigger deployment

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📈 Final Architecture

GitHub → GitHub Actions → Docker Hub
                        ↘ SSH
                          AWS EC2 → Docker → Flask App (port 5000)

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🧠 Key Takeaways

• CI/CD automation reduces manual deployment work

• Docker + GitHub Actions is an efficient pipeline combo

• AWS EC2 gives full control over deployments

• Real-world projects teach more than theory ever could!

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📌 Final Notes

To save AWS credits, my EC2 instance is currently turned off.
You can still clone the project and run locally:

docker build -t flask-cicd .
docker run -p 5000:5000 flask-cicd

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🔗 Links

• 💻 GitHub Repo

• 🐳 Docker Image