How can I install packages on my heroku app?

Question

I have an app that makes use of shortuuid (https://pypi.python.org/pypi/shortuuid/0.1) that is working fine locally when I run it with runapp.py:

import os

from paste.deploy import loadapp
from waitress import serve

if __name__ == "__main__":
    port = int(os.environ.get("PORT", 5000))
    app = loadapp('config:production.ini', relative_to='.')

    serve(app, host='0.0.0.0', port=port)

It does not work, however, when I try and run it with ../bin/pserve development.ini. I get the error: import error: no module named shortuuid. When I push it to heroku I get the same error. I have installed shortuuid into my virtual environment where my app is run and can only conclude that the absence of this installation on heroku is whats causing the problem.

I have tried replacing the development.ini code with the production.ini code and it still does not work so I assume its something else (maybe the import os line on runapp.py?)

Answer 1

I usually create a requirements.txt file that contains the packages:

Flask==0.9
Jinja2==2.6
Werkzeug==0.8.3
distribute==0.6.27
wsgiref==0.1.2

Flask-Cache==0.10.0

gunicorn==0.17.2

You can create that file with pip:

$ pip freeze > requirements.txt

Answer 2

Place a requirements.txt in the root directory of your git repo, with your required dependencies (specified in pip/easy-install format).

Example taken from the Heroku website:

Flask==0.8
Jinja2==2.6
Werkzeug==0.8.3
certifi==0.0.8
chardet==1.0.1
distribute==0.6.24
gunicorn==0.14.2
requests==0.11.1