Gunicorn for production serving in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Gunicorn in the context of Flask applications?

Gunicorn is a production-ready web server that runs Flask applications efficiently by managing multiple worker processes to handle requests.

beginner

Why should you use Gunicorn instead of Flask's built-in server in production?

Flask's built-in server is for development only; it is single-threaded and not optimized for handling many users. Gunicorn can handle multiple requests concurrently and is more stable for production use.

beginner

How do you start a Flask app with Gunicorn on the command line?

Use the command: gunicorn app:app where the first app is the Python file name (without .py) and the second app is the Flask application instance.

intermediate

What does the -w option do when running Gunicorn?

The -w option sets the number of worker processes Gunicorn will use to handle requests. More workers can handle more users at the same time.

beginner

Name one benefit of using multiple Gunicorn workers for a Flask app.

Multiple workers allow the app to handle many requests at once, improving speed and reliability, especially under heavy traffic.

What is the main reason to use Gunicorn with Flask in production?

A To write Flask code faster

B To create HTML templates

C To debug Flask applications

D To handle multiple requests efficiently

Gunicorn manages multiple worker processes to handle many requests efficiently, which Flask's built-in server cannot do well.

Which command starts a Flask app named 'app.py' with Gunicorn?

A gunicorn app:app

B flask run app.py

C python app.py

D gunicorn run app.py

The correct Gunicorn command uses the format 'gunicorn filename:app_instance', so 'gunicorn app:app' runs the app in 'app.py'.

What does the '-w 4' option do when running Gunicorn?

A Runs on port 4

B Runs 4 worker processes

C Runs 4 threads per worker

D Limits requests to 4 per second

The '-w' option sets the number of worker processes; '-w 4' means Gunicorn will use 4 workers.

Is Flask's built-in server suitable for production use?

A Only if you use debug mode

B Yes, it is optimized for production

C No, it is only for development

D Only on Windows systems

Flask's built-in server is not designed for production; it lacks performance and security features needed for real users.

Which of these is a benefit of using Gunicorn workers?

A Improved ability to handle many users at once

B Automatic code formatting

C Faster HTML rendering

D Built-in database support

Multiple workers let Gunicorn handle many requests simultaneously, improving app responsiveness.

Explain why Gunicorn is preferred over Flask's built-in server for production.

Think about how many users your app can serve at once.

Describe how to run a Flask app with Gunicorn and how to adjust its performance.

Focus on the command line and worker settings.