Lab 19: Clone and Containerize Flask Web App¶

Objective

By the end of this lab, you will be able to: - Clone a Flask app from GitHub - Understand the app’s folder structure - Add a Dockerfile - Build and run the Flask app as a container

Prerequisites

Docker installed (Lab 17)
Git configured (Lab 18)

Step 1: Clone the Flask Web App Repo¶

1.1 Navigate to workspace directory¶

cd ~
mkdir devops-labs && cd devops-labs

1.2 Clone the Repository¶

git clone https://github.com/Sid-Trainings/flask-sample-webapp.git
cd flask-sample-webapp

Step 2: Review App Structure¶

You should see:

-README.md
-app.py
-app.yaml
-app_test.py
-requirements-test.txt
-requirements.txt
-templates/
  -index.html

app.py: Main Flask app entry point
requirements.txt: Python dependencies
templates/index.html: The HTML5 Bootstrap page

Step 3: Create Dockerfile¶

3.1 Create File¶

nano Dockerfile

3.2 Paste Below Content¶

# Use Python base image
FROM python:3.9-slim

# Set work directory
WORKDIR /app

# Copy files
COPY . /app

# Install dependencies
RUN pip install --no-cache-dir -r requirements.txt

# Expose port
EXPOSE 5000

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

Save and exit.

Press Crtl+O --> Enter and Crtl+X to save the file in nano editor

Step 4: Build Docker Image¶

docker build -t flask-demo-app .

Step 5: Run Flask App Container¶

docker run -d -p 5000:5000 flask-demo-app

Access the app in browser:

http://localhost:5000

✅ Verification¶

If the app loads with your styled HTML page and sections (Welcome, Docker Ready, etc.), you’ve successfully containerized and deployed it locally.

🚀 What’s Next?¶

In Lab 20, you'll push this Docker image to Docker Hub.