在flask / gunicorn中初始化应用的地方

Question

I'm using Flask/Gunicorn to run a web application and have a question about the lifecycle management. I have more experience in the Java world with servlets.

I'm creating a restful interface to a service. The service is always running on the server and communicates and controls with a set of sub-servers. In Java, my service would be created and initialized (eg the setup traditionally found in main() ) through listeners and servlet initialization methods.

Where would the equivalent setup and configuration be in Flask? I'm thinking of tasks like creating a database connection pool, sending hello messages to the sub-servers, resetting the persisted system state to initial values, etc.

Would that go in the before_first_request method of Flask?

Based on @Pyrce's comments I think I could create a main.py :

app = Flask(your_app_name)

#initialization code goes here

and then run with:

>gunicorn main:app

Answer 1

You can still use the same main() method paradigm. See this starter code below:

app = Flask(your_app_name) # Needs defining at file global scope for thread-local sharing

def setup_app(app):
   # All your initialization code
setup_app(app)

if __name__ == '__main__':
    app.run(host=my_dev_host, port=my_dev_port, etc='...')

The before_first_request method could also handle all of those items. But you'll have the delay of setup on first request rather than on server launch.