Step 1: Create Your Flask Application First, create a file named app.py with the following content:

Python app.py

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, Docker!'

if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')

Step 2: Requirements Create a file named requirements.txt in the same directory as your app.py with the following content:

makefile

flask==2.0.1

Step 3: Create a Dockerfile Next, create a Dockerfile in the same directory with the following content:

Dockerfile

# Use an official Python runtime as a parent image
FROM python:3.8-slim

# Set the working directory in the container
WORKDIR /usr/src/app

# Copy the current directory contents into the container at the working directory
COPY . .

# Install any needed packages specified in requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

# Make port 5000 available to the world outside this container
EXPOSE 5000

# Define environment variable
ENV NAME World

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

Step 4: Build Your Docker Image Open a terminal and navigate to the directory containing your Dockerfile, then build your Docker image:

docker build -t python-flask-sample .

Step 5: Run Your Docker Container After the build completes, run your Docker container:

docker run -p 5000:5000 python-flask-sample

Step 6: Verify Open a web browser and go to http://localhost:5000. You should see Hello, Docker! displayed.