How to install gunicorn?

Question

Flask

Good evening.
I'm trying to deploy a Flask project on heroku.com.
Made Procfile:
web: gunicorn project:app
Checked, everything is started locally.
foreman check
Recognizes the Procfile as valid.
Made the same requirements.txt. double-checked it has gunicorn.
gunicorn==19.1.1
Next, I push everything to Heroku.
I run:
heroku ps:scale web=1
When checking active, it gives out:

=== web (1X): `gunicorn project:app`
web.1: crashed 2015/03/10 18:17:22 (~ 3s ago)

Screenshot of logs and errors:


I also tried to install gunicorn manually
heroku run pip install gunicorn
Restart and the result is the same.
What am I doing wrong, why is gunicorn not installed?

Answer 1

Locally tested running with gunicorn?

pip install gunicorn

(venv) $ gunicorn manage:app

Well
-r requirements/prod.txt

gunicorn==18.0
psycopg2==2.5.1