Python, Flask, Gunicorn Error: Unrecognized Arguments

Question

I am running my app app.py using Python and Flask. I'm trying to deploy it to Heroku, and I followed the steps in this tutorial, including making a Procfile and requirements.txt. However, whenever I run heroku local, I get the following error:

web.1  | [2015-09-26 17:36:32 -0400] [19422] [INFO] Starting gunicorn 19.3.0
web.1  | [2015-09-26 17:36:32 -0400] [19422] [INFO] Listening at: http://0.0.0.0:5000 (19422)
web.1  | [2015-09-26 17:36:32 -0400] [19422] [INFO] Using worker: sync
web.1  | [2015-09-26 17:36:32 -0400] [19425] [INFO] Booting worker with pid: 19425
web.1  | usage: gunicorn [-h] [--auth_host_name AUTH_HOST_NAME]
web.1  | gunicorn: error: unrecognized arguments: app:app
web.1  | [2015-09-26 17:36:32 -0400] [19425] [INFO] Worker exiting (pid: 19425)

I've deployed apps successfully on Heroku before, but never have gotten this error. My Procfile is simply one line: web: gunicorn app:app.

Can anybody tell me how to fix this?

UPDATE: Modified some of my code and now when I run heroku local, it runs fine:

web.1  | [2015-09-28 18:52:13 -0400] [70650] [INFO] Starting gunicorn 19.3.0
web.1  | [2015-09-28 18:52:13 -0400] [70650] [INFO] Listening at: http://0.0.0.0:5000 (70650)
web.1  | [2015-09-28 18:52:13 -0400] [70650] [INFO] Using worker: sync
web.1  | [2015-09-28 18:52:13 -0400] [70653] [INFO] Booting worker with pid: 70653

However, when I deploy my Heroku app, I get an Application Error, and when I check the logs, I see the same error as before:

2015-09-28T22:50:54.775077+00:00 app[web.1]: 2015-09-28 22:50:54 [3] [INFO] Starting gunicorn 18.0
2015-09-28T22:50:54.776176+00:00 app[web.1]: 2015-09-28 22:50:54 [3] [INFO] Using worker: sync
2015-09-28T22:50:54.776052+00:00 app[web.1]: 2015-09-28 22:50:54 [3] [INFO] Listening at: http://0.0.0.0:24995 (3)
2015-09-28T22:50:54.786067+00:00 app[web.1]: 2015-09-28 22:50:54 [9] [INFO] Booting worker with pid: 9
2015-09-28T22:50:56.004336+00:00 heroku[web.1]: State changed from starting to up
2015-09-28T22:51:42.659042+00:00 heroku[router]: at=error code=H13 desc="Connection closed without response" method=GET path="/" host=bobawithjames.herokuapp.com request_id=1afab4c0-484e-456b-be05-3086ee0711cd fwd="160.39.250.29" dyno=web.1 connect=1ms service=39ms status=503 bytes=0
2015-09-28T22:51:42.604331+00:00 app[web.1]:                 [--noauth_local_webserver]
2015-09-28T22:51:42.604323+00:00 app[web.1]: usage: gunicorn [-h] [--auth_host_name AUTH_HOST_NAME]
2015-09-28T22:51:42.604335+00:00 app[web.1]:                 [--auth_host_port [AUTH_HOST_PORT [AUTH_HOST_PORT ...]]]
2015-09-28T22:51:42.633611+00:00 app[web.1]: gunicorn: error: unrecognized arguments: hello:app

Anyone know what's going on now?

Answer 1

I was able to solve this problem by replacing args = parser.parse_args() in my app with args, unknown = parser.parse_known_args()

Answer 2

The issue was with having argparse in my script that is being ran by flask/gunicorn. Put these inside a:

if __name__ == "__main__":
    import argparse
    ...

This way if it's ran directly you can still parse the arguments running it standalone.