Getting Started with Python: Flask + Gunicorn Hello World Tutorial

In this tutorial, we will be going through the process of creating a simple Hello World web application using Flask and Gunicorn in Python. Flask is a lightweight web framework that makes it easy to create web applications in Python, while Gunicorn is a WSGI HTTP server that can be used to serve Flask applications.

Before starting the tutorial, make sure you have Python installed on your system. You can download Python from the official website: https://www.python.org/downloads/. Flask and Gunicorn can be installed using pip, the Python package manager.

Step 1: Setting up the virtual environment
It is always a good practice to create a virtual environment for your Python projects to avoid conflicts with system-wide packages. To create a virtual environment, you can use the following commands in your terminal:

$ python3 -m venv myenv
$ source myenv/bin/activate

Step 2: Installing Flask and Gunicorn
Once you have activated the virtual environment, you can install Flask and Gunicorn using pip:

$ pip install Flask gunicorn

Step 3: Creating the Flask application
Now, let’s create a simple Flask application that will display "Hello World" when accessed. Create a new Python file named app.py and add the following code:

from flask import Flask

app = Flask(__name__)

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

Save the file and you have created a simple Flask application that defines a route for the root URL (/) and returns "Hello World" when accessed.

Step 4: Running the Flask application with Gunicorn
To run the Flask application using Gunicorn, you can use the following command in your terminal:

$ gunicorn -b 0.0.0.0:8000 app:app

This command starts the Gunicorn server and binds it to the IP address 0.0.0.0 on port 8000, serving the Flask application defined in the app variable in the app.py file.

Step 5: Accessing the Hello World web application
Once the Gunicorn server is running, you can access the Hello World web application by opening a web browser and navigating to http://localhost:8000. You should see the text "Hello World" displayed on the page, indicating that the Flask application is running successfully.

Congratulations! You have successfully created a simple Hello World web application using Flask and Gunicorn in Python. You can now further customize your Flask application by adding more routes and functionality as needed. Happy coding!