Heroku Gunicorn Procfile

Question

I have a hard time finding documentation for creating Procfiles using flask with gunicorn and Heroku. Somewhere I found that the syntax is: web: gunicorn my_folder.my_module:app. But I can't make it work. It only works for me when my python script: hello.py is in the root folder of the app. When I put it in a subfolder called app and create a Procfile: web: gunicorn app.hello:app it doesn't work. Only when I use web: gunicorn hello:app and my python script is in the root folder. Can someone explain me the proper syntax of Procfiles for gunicorn on Heroku, and how to make it work when the python script is in a subfolder?

Answer 1

Gunicorn takes a flag, --chdir, that lets you select which directory your Python app lives in. So, if you have a directory structure like:

my-project/
  Procfile
  my_folder/
    my_module.py

and my_module.py contains:

app = Flask(__name__, ...)

You can put the following in your Procfile:

web: gunicorn --chdir my_folder my_module:app