Containerizing a simple Python Flask app using Docker

Containerization is a method of packaging, distributing, and managing applications within a container, which allows for seamless deployment across different environments. Docker is a popular platform for containerization, and it provides a way to run applications in isolated environments called containers.

In this article, we will cover how to containerize a simple Python Flask app using Docker. Python Flask is a lightweight web framework for building web applications, and Docker will allow us to package and deploy the Flask app in a consistent and predictable manner.

Step 1: Create a simple Python Flask app

First, let’s create a simple Python Flask app. Create a new directory for the app and create a file called app.py with the following content:

“`python
from flask import Flask

app = Flask(__name__)

@app.route(‘/’)
def hello_world():
return ‘Hello, World!’

if __name__ == ‘__main__’:
app.run(debug=True, host=’0.0.0.0′)
“`

Step 2: Create a Dockerfile

Next, we need to create a Dockerfile to define the image for our Flask app. Create a file called Dockerfile in the same directory as app.py with the following content:

“`Dockerfile
FROM python:3.8-slim

WORKDIR /app

COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt

COPY . .

CMD [ “python”, “app.py” ]
“`

Step 3: Create a requirements file

We also need to create a requirements.txt file to specify the dependencies for our Flask app. Create a file called requirements.txt with the following content:

“`
Flask
“`

Step 4: Build and run the Docker image

Now that we have our Flask app and Dockerfile defined, we can build and run the Docker image. Open a terminal and navigate to the directory containing app.py and Dockerfile. Run the following commands to build and run the Docker image:

“`
docker build -t simple-flask-app .
docker run -p 5000:5000 simple-flask-app
“`

Now you should be able to access the Flask app running in a Docker container at http://localhost:5000.

Conclusion

Containerizing a simple Python Flask app using Docker is a straightforward process that allows for easy deployment and management of the app in a containerized environment. By following the steps outlined in this article, you can quickly containerize your own Python Flask apps using Docker.