Dockerfile

# Use the official Python image from the Docker Hub
FROM python:3.9-slim

# Set the working directory in the container
# this allows for any subsequent commands to be run from this directory
WORKDIR /app

# Copy the current directory contents into the container at /app
# . indicates the directory where the Dockerfile is located and copies all 
# files in that directory into our container working directory
COPY . /app

# Install any needed packages specified in requirements.txt
# using --no-cache-dir to not cache the packages and save space
RUN pip install --no-cache-dir -r requirements.txt

# Make port 8000 available to the world outside this container
EXPOSE  80

# Define environment variable
# FLASK_APP is a framework specific environmnent variable that tells
# the flask command where the application is located

#without this the flask run command will not know what app to run.
ENV FLASK_APP=app.py

# Run app.py when the container launches
# 0.0.0.0 sets the application to listen on all network interfaces

#a more secure option would be to specify the exact IP you plan to use 
# (e.g.API gateway interface)
CMD ["python", "app.py"]