apache – Auto reloading python Flask app upon code changes

The current recommended way is with the flask command line utility.

https://flask.palletsprojects.com/en/1.1.x/quickstart/#debug-mode

Example:

$ export FLASK_APP=main.py
$ export FLASK_ENV=development
$ flask run

or in one command:

$ FLASK_APP=main.py FLASK_ENV=development flask run

If you want different port than the default (5000) add --port option.

Example:

$ FLASK_APP=main.py FLASK_ENV=development flask run --port 8080

More options are available with:

$ flask run --help

FLASK_APP can also be set to module:app or module:create_app instead of module.py. See https://flask.palletsprojects.com/en/1.1.x/cli/#application-discovery for a full explanation.

If you are talking about test/dev environments, then just use the debug option. It will auto-reload the flask app when a code change happens.

app.run(debug=True)

Or, from the shell:

$ export FLASK_DEBUG=1
$ flask run

http://flask.pocoo.org/docs/quickstart/#debug-mode

apache – Auto reloading python Flask app upon code changes

In test/development environments

The werkzeug debugger already has an auto reload function available that can be enabled by doing one of the following:

app.run(debug=True)

or

app.debug = True

You can also use a separate configuration file to manage all your setup if you need be. For example I use settings.py with a DEBUG = True option. Importing this file is easy too;

app.config.from_object(application.settings)

However this is not suitable for a production environment.

Production environment

Personally I chose Nginx + uWSGI over Apache + mod_wsgi for a few performance reasons but also the configuration options. The touch-reload option allows you to specify a file/folder that will cause the uWSGI application to reload your newly deployed flask app.

For example, your update script pulls your newest changes down and touches reload_me.txt file. Your uWSGI ini script (which is kept up by Supervisord – obviously) has this line in it somewhere:

touch-reload = /opt/virtual_environments/application/reload_me.txt

I hope this helps!