Failing to combine python buildpack with R buildpack

[Toekan]

Hi,

I'm trying to use this buildpack and the heroku maintained Python buildpack in one app, when trying to do

heroku run python

after installing both (git push heroku master) ImportError: No module named site from Python. When deleting the R buildpack and rebuilding the slug, I do manage to run Python. I assume this buildpack changes some things in the slug environment? Does anyone how to solve this problem?

Some extra information:
I have no Procfile. Only trying to run a one-off dyno, hence heroku run.
R does work, both when also installing the python buildpack and when not.
I have a init.R (which succesfully installs some packages) and requirements.txt and runtime.txt files for the python build (again, they do get recognised, while building the slug the correct packages get pip installed)

[virtualstaticvoid]

Which python library are you using? Assuming you are calling R from Python.

[Toekan]

Not trying to call R from Python, just trying to have a slug where I can run both my R scripts and my Python scripts. Python basically fails from the moment when I try to launch it. That's why I'm so surprised that (and took me a while to realise) that Python works when I get rid of the R buildpack.

[virtualstaticvoid]

Ok, I'll try replicate your issue.

[virtualstaticvoid]

Ok, I've found the issue. It has to do with the PYTHONHOME environment variable.

Deploy your app with both buildpacks, then run heroku run /bin/bash and run unset PYTHONHOME and then your python or R commands, it works.

I'm going to look into what the differences are between deploying with and without the R buildpack, which may explain this.

[virtualstaticvoid]

Mmm, seems it is rather the PATH environment variable, since with the R buildpack included, which python resolves to /usr/bin/python, whereas with only the python buildpack it resolves to /app/.heroku/python/bin/python.

[Toekan]

I've done the unset PYTHONHOME, which indeed makes python and R work, but I can't import the installed python packages now (which I can when only using the python buildpack), I get the standard:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named pandas

Thanks for all (and very quick) help btw! :)

[virtualstaticvoid]

np. Correcting the PATH variable will fix this.

I.e. After running heroku run /bin/bash, run export PATH=/app/.heroku/python/bin:/bin:/app/.tools/fakeroot/bin:/app/.tools/fakechroot/sbin:/app/.tools/fakechroot/bin:./bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/bin:/usr/bin

I'm researching a better way to solve this, since compile#L308 isn't playing nicely with other buildpacks.

[virtualstaticvoid]

This gist with the code to replicate the issue.

[kwent]

Running into this issue as well... :(

[nick-solly]

Also hitting this issue. Any update, much appreciated.

[virtualstaticvoid]

I recommend using heroku-docker-r instead, since it works in a compatible way with your project files, requires a very simple/easy change, and doesn't suffer from the issues of the current (heroku-16) buildpack version.