Running Flask app on Heroku

Question

I'm trying to run a Flask app on Heroku and I'm getting some frustrating results. I'm not interested in the ops side of things. I just want to upload my code and have it run. Pushing to the Heroku git remote works fine ( git push heroku master ), but when I tail the logs ( heroku logs -t ) I see the following error:

2014-11-08T15:48:50+00:00 heroku[slug-compiler]: Slug compilation started
2014-11-08T15:48:58+00:00 heroku[slug-compiler]: Slug compilation finished
2014-11-08T15:48:58.607107+00:00 heroku[api]: Deploy 2ba1345 by <my-email-address>
2014-11-08T15:48:58.607107+00:00 heroku[api]: Release v5 created by <my-email-address>
2014-11-08T15:48:58.723704+00:00 heroku[web.1]: State changed from crashed to starting
2014-11-08T15:49:01.458713+00:00 heroku[web.1]: Starting process with command `gunicorn app:app`
2014-11-08T15:49:02.538539+00:00 app[web.1]: bash: gunicorn: command not found
2014-11-08T15:49:03.340833+00:00 heroku[web.1]: Process exited with status 127
2014-11-08T15:49:03.355031+00:00 heroku[web.1]: State changed from starting to crashed
2014-11-08T15:49:04.462248+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=blueprnt.herokuapp.com request_id=e7f92595-b202-4cdb-abbc-309dcd3a04bc fwd="54.163.35.91" dyno= connect= service= status=503 bytes=

Here's the pertinent files:

Procfile

web: gunicorn app:app
heroku ps:scale web

requirements.txt

Flask==0.10.1
Flask-Login==0.2.11
Flask-WTF==0.10.2
Jinja2==2.7.3
MarkupSafe==0.23
Unidecode==0.04.16
WTForms==2.0.1
Werkzeug==0.9.6
awesome-slugify==1.6
blinker==1.3
gnureadline==6.3.3
gunicorn==19.1.1
ipdb==0.8
ipython==2.3.0
itsdangerous==0.24
peewee==2.4.0
py-bcrypt==0.4
pytz==2014.7
regex==2014.10.24
wsgiref==0.1.2
wtf-peewee==0.2.3

app.py (the run portion)

# Run application
if __name__ == '__main__':
    # from os import environs
    # app.run(debug=False, port=environ.get("PORT", 5000), processes=2)
    app.run(debug=True, port=33507)

I've tried both the answer from this thread and from this thread . When I try to shell into Heroku to investigate ( heroku run bash ) it appears that something is wrong with my app's environment:

(blueprnt)☀  website [master] heroku run bash
/Users/andymatthews/.rvm/gems/ruby-1.9.3-p125/gems/heroku-3.15.0/lib/heroku/helpers.rb:91: warning: Insecure world writable dir /usr/local in PATH, mode 040777
Running `bash` attached to terminal... up, run.8540
~ $ ls
Gruntfile.js  __init__.py  fixtures   models.py     requirements.txt       static     vendor
Procfile      app.py       forms.py   node_modules  settings.py        templates  views
README.md     blueprnt.db  mixins.py  package.json  site-theme-assets.zip  utils.py
~ $ pwd
/app
~ $ whoami
u15880
~ $ which pip
~ $ which git
/usr/bin/git
~ $ pip install -r requirements.txt
bash: pip: command not found

Would really love some assistance. In the past when I've deployed apps to Heroku, I haven't had any problem. But this app is more complicated than those others.

Answer 1

this isn't an answer but had to include a decent sized code block

Part of the problem with your current traceback is it does not really provide relevant information for debugging. You can log the errors on heroku then use heroku log to get a more substantial traceback of your app's errors.

Do this by adding a handler on to your app.logger . Heroku will pick up data from sys.stderr so you can use a logging.StreamHandler class

import logging
import sys
from logging import Formatter

def log_to_stderr(app):
  handler = logging.StreamHandler(sys.stderr)
  handler.setFormatter(Formatter(
    '%(asctime)s %(levelname)s: %(message)s '
    '[in %(pathname)s:%(lineno)d]'
  ))
  handler.setLevel(logging.WARNING)
  app.logger.addHandler(handler)

if __name__ == '__main__':
  log_to_stderr(app)
  app.run()