Deploying to Heroku not working on v0.3

[samharrison7]

Description

I've been struggling to get Voila to deploy to Heroku recently, and have just figured that I am only having issues where I'm using version 0.3. For example, using the template repo (https://github.com/voila-dashboards/voila-heroku) now doesn't work on Heroku as it installs the 0.3 version (I had to update the runtime.txt to use 3.8.10 as 3.7.5 isn't available on the default Heroku-20 stack).

Specifically I get a timeout error in the Heroku logs. It looks like the Voila server starts up okay but doesn't manage to send anything when a page is requested:

2021-12-18T13:09:03.238707+00:00 heroku[web.1]: Starting process with command `voila --port=26507 --no-browser --template=material --enable_nbextensions=True notebooks/bqplot.ipynb`
2021-12-18T13:09:05.949936+00:00 app[web.1]: [Voila] Using /tmp to store connection files
2021-12-18T13:09:05.950308+00:00 app[web.1]: [Voila] Storing connection files in /tmp/voila_l56jo0cr.
2021-12-18T13:09:05.950375+00:00 app[web.1]: [Voila] Serving static files from /app/.heroku/python/lib/python3.8/site-packages/voila/static.
2021-12-18T13:09:06.180485+00:00 app[web.1]: [Voila] Voilà is running at:
2021-12-18T13:09:06.180486+00:00 app[web.1]: http://localhost:26507/
2021-12-18T13:09:13.000000+00:00 app[api]: Build succeeded
2021-12-18T13:10:03.342378+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch
2021-12-18T13:10:03.368529+00:00 heroku[web.1]: Stopping process with SIGKILL
2021-12-18T13:10:03.528533+00:00 heroku[web.1]: Process exited with status 137
2021-12-18T13:10:03.609381+00:00 heroku[web.1]: State changed from starting to crashed

If I change the requirements.txt to voila==0.2.16, it works as expected. Running Heroku locally also works (heroku local) as expected, even with version 0.3. I tried to set max boot time to 180 secs and it still didn't work.

Reproduce

To reproduce, follow the instructions in https://github.com/voila-dashboards/voila-heroku, but change the runtime.txt file to python-3.8.10 (or anything else on Heroku-20).

[trungleduc]

Hello @samharrison7 ,
From 0.3.0, Voila will not listen on all interfaces by default (#926) for security reasons. In the case of Heroku, you need to add --Voila.ip=0.0.0.0 to your command in the Procfile to make it works.

We will update https://github.com/voila-dashboards/voila-heroku to reflect the change in 0.3.0.

[samharrison7]

Ah perfect, makes sense. Thanks for the quick reply!