How do I run a flask app in gunicorn if I used the application factory pattern?

Question

I wrote a flask app using the application factory pattern. That means it doesn't create an app instance automatically when you import it. You have to call create_app for that. Now how do I run it in gunicorn?

Answer 1

Create a file wsgi.py under your project with the following contents, then point Gunicorn at it.

from my_project import create_app

app = create_app()

gunicorn -w 4 my_project.wsgi:app
# -w 4 specifies four worker processes

Gunicorn allows specifying a function call like my_project:create_app(). For most cases, you can the skip making a wsgi.py file and tell Gunicorn how to create your app directly.

gunicorn -w 4 my_project:create_app()

Note that you may have to put the name in quotes for some shells.

gunicorn -w 4 "my_project:create_app()"

Answer 2

You need to create_app() with specific factory config in wsgi.py just like manage.py or runserver.py. See the code below:

from your_app import create_app

app = create_app(os.getenv('FLASK_CONFIG') or 'dev')

if __name__ == "__main__":
    app.run()

And then, you could run command gunicorn -w 4 -b 0.0.0.0:5000 wsgi:app to run your application.