Failed deployment on Heroku

Dash Python
1

Hi,

I am having a hard time deploying a Dash app on Heroku. I set up my virtual environment as follows:

git init        
virtualenv -p python3 venv # to force the use of python 3 otherwise it uses python 2.7 for some reason
source venv/bin/activate

then install packages

pip3 install dash
pip3 install dash-renderer
pip3 install dash-core-components
pip3 install dash-html-components
pip3 install plotly
pip3 install gunicorn
pip freeze > requirements.txt

then deploy

git add .
git commit -m 'deployment 1'
git push heroku master

But I get the following error

...
remote:          Downloading https://files.pythonhosted.org/packages/c5/60/6ac26ad05857c601308d8fb9e87fa36d0ebf889423f47c3502ef034365db/functools32-3.2.3-2.tar.gz
remote:            Complete output from command python setup.py egg_info:
remote:            This backport is for Python 2.7 only.
remote:
remote:            ----------------------------------------
remote:        Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-j0kwb7bi/functools32/
remote:  !     Push rejected, failed to compile Python app.
remote:
remote:  !     Push failed

Any ideas why this might be happening?

2

I’m not familiar with that particular error message, and it’s hard to tell without seeing all your application code, but be sure to reference the Heroku deployment example by @chriddyp if you haven’t done so already.
There’s also great step-by-step walk-through of Heroku deployment for Dash here – see pages 90 and following – Hat tip to Jose Portilla for providing this documentation.
For me, the most common error was omitting the line server = app.server after app = dash.Dash().

3

Thanks for the reply Austin. I went through the Heroku deployment example by @chriddyp. It used to work, but I get the same error message with that now so I guess there is something more fundamentally wrong with my python setup.

The app works fine locally but only falls over when deployed on Heroku

One other thing, looking at a related post I noticed that my virtual environment was using python 2.7. I forced it to use python 3.6 (virtualenv -p python3 venv) but I still get the same error message. Its strange that I should have to force it to install Python 3.6 though.

4

I just figured it out. I removed the following from the requirements.txt file:

functools32==3.2.3.post2
pkg-resources==0.0.0

And now it works.