🚀 Day 40: CI/CD with Flask + Docker + GitHub Actions | #100DaysOfDevOps

Welcome to Day 40 of my #100DaysOfDevOps! Today, I built a CI/CD pipeline for a Python Flask application, containerized it with Docker, and automated the build and deployment process using GitHub Actions. Let’s dive into this exciting journey! 🐍🐳💥 #DevOps #CI/CD

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🔧 Project Overview: Flask App with Docker CI/CD

The goal of this project is to create a simple Flask application, containerize it using Docker, and set up a GitHub Actions workflow to automatically build and push the Docker image to Docker Hub whenever code is pushed to the main branch. #Flask #Docker #GitHubActions

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🗂 Project Structure

Here’s the structure of the project:

flask-ci-cd-demo/
├── app/
│   ├── app.py           # Flask app logic
│   └── requirements.txt # Python dependencies
├── Dockerfile           # Docker configuration
├── .dockerignore        # Ignore unnecessary files in Docker context
├── .gitignore           # Ignore local dev/config files
├── .github/
│   └── workflows/
│       └── ci-cd.yml    # GitHub Actions workflow file
└── README.md            # Project details

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🛠️ Step 1: Set Up the Project

Create the project directory and initialize a Python environment:

mkdir flask-ci-cd-demo && cd flask-ci-cd-demo
mkdir app

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🐍 Step 2: Create the Flask Application

app/app.py

Create a simple Flask app:

from flask import Flask
app = Flask(__name__)

@app.route("/")
def home():
    return "🚀 Hello from Flask CI/CD Pipeline!"

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

This code sets up a Flask server that responds with a message at http://localhost:5000. #Python #Flask

app/requirements.txt

List the dependencies:

flask

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🐳 Step 3: Create the Dockerfile

Create a Dockerfile to containerize the Flask app:

# Use official Python image
FROM python:3.10-slim

# Set work directory
WORKDIR /app

# Copy files and install dependencies
COPY app/requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy source code
COPY app/ .

# Run the Flask app
CMD ["python", "app.py"]

Why this structure?

• Using python:3.10-slim keeps the image lightweight.

• Copying requirements.txt first allows Docker to cache the dependency layer, speeding up builds if only app.py changes. #Docker #Optimization

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📦 Step 4: Optimize with .dockerignore and .gitignore

.dockerignore

Prevent unnecessary files from being included in the Docker image:

# Git and version control
.git
.gitignore

# Python bytecode
__pycache__/
*.pyc

# Virtual environments
env/
venv/
ENV/

# Editor settings
.vscode/
.idea/

# System files
.DS_Store

# GitHub Actions config
.github/

.gitignore

Ignore local development and temporary files:

# Python
__pycache__/
*.pyc
*.pyo
*.pyd
env/
venv/
ENV/
*.env

# Editor settings
.vscode/
.idea/

# System files
.DS_Store
Thumbs.db

# Logs
*.log

# Docker artifacts
*.tar

These files ensure clean builds and repositories by excluding irrelevant files. #BestPractices

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⚙️ Step 5: Set Up GitHub Actions Workflow

Create the workflow file at .github/workflows/ci-cd.yml:

name: Flask CI/CD

on:
  push:
    branches:
      - main

jobs:
  build-and-deploy:
    runs-on: ubuntu-latest

    steps:
      - name: 📥 Checkout code
        uses: actions/checkout@v4

      - name: 🐍 Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: '3.10'

      - name: 📦 Install dependencies
        run: pip install -r app/requirements.txt

      - name: ✅ Run tests
        run: echo "No tests yet"

      - name: 🐳 Build Docker image
        run: docker build -t ritesh355/flask-ci-cd-demo .

      - name: 📤 Push to Docker Hub
        run: |
          echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
          docker tag ritesh355/flask-ci-cd-demo ritesh355/flask-ci-cd-demo:latest
          docker push ritesh355/flask-ci-cd-demo:latest

Key Points:

• Triggers on pushes to the main branch.

• Sets up Python 3.10 and installs dependencies.

• Builds the Docker image and pushes it to Docker Hub.

• Uses GitHub Secrets for secure Docker Hub authentication. #GitHubActions #Automation

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🔐 Step 6: Configure Docker Hub Secrets

To enable Docker Hub pushes, add these secrets to your GitHub repository:

• DOCKER_USERNAME: Your Docker Hub username (ritesh355).

• DOCKER_PASSWORD: Your Docker Hub access token (not your password).

Add them via:

1. Go to GitHub Repo → Settings → Secrets and variables → Actions.

2. Click New repository secret and add DOCKER_USERNAME and DOCKER_PASSWORD. #Security #DockerHub

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🚀 Step 7: Push to GitHub

Push your project to GitHub:

git init
git remote add origin https://github.com/ritesh355/flask-ci-cd-demo.git
git add .
git commit -m "Add Flask CI/CD demo with Docker and GitHub Actions"
git push -u origin main

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✅ Step 8: Verify the CI/CD Pipeline

1. Go to your GitHub repo → Actions tab.

2. Watch the Flask CI/CD workflow run. It will:

   • Install Python dependencies.

   • Build the Docker image.

   • Push the image to ritesh355/flask-ci-cd-demo:latest on Docker Hub.

3. Visit Docker Hub to confirm the image is published.

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🧪 Step 9: Test the Docker Image Locally

To verify the image, run it locally (if you have Docker installed):

docker pull ritesh355/flask-ci-cd-demo:latest
docker run -p 5000:5000 ritesh355/flask-ci-cd-demo

Open your browser and visit http://localhost:5000. You should see:

"🚀 Hello from Flask CI/CD Pipeline!"

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📌 Learnings from Day 13

• Built an end-to-end CI/CD pipeline for a Flask app using GitHub Actions.

• Used .dockerignore and .gitignore to optimize Docker builds and keep the repository clean.

• Secured Docker Hub credentials with GitHub Secrets.

• Automated Docker image builds and pushes to Docker Hub. #Learning #DevOpsJourney

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📈 Benefits

• Automation: Push code, and GitHub Actions handles the rest.

• Efficiency: .dockerignore reduces image size and build time.

• Security: Sensitive credentials are safely stored in GitHub Secrets.

• Scalability: Ready to extend with tests or deployment steps.

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🔗 Useful Links

• 💻 GitHub Repo

• 📦 Docker Hub

• ✍️ My Blog

#Portfolio #Networking

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🎉 Congratulations!

You’ve successfully built a CI/CD pipeline for a Flask app with Docker and GitHub Actions! Keep rocking your #100DaysOfDevOps journey! 💪 #KeepLearning

Need help? Drop a comment or question, and I’ll guide you through any issues!