How to add python dependencies to heroku node server?

Question

I have a Heroku app that's running Node, but I need to be able to run Python scripts on this server. I'm trying to install my Python dependencies but can't get it to work.

I've added both python and node build packs to my project, I've create a virtual environment and successfully installed requirements.txt, but I continue to get module not found errors.

How can I properly install Python packages on a Heroku Node server?

Heroku shows that I have correctly set both buildpacks:

heroku buildpacks --app <my app>

Outputs:

1. heroku/nodejs
2. heroku/python 

If I try to install requirements.txt:

$ pip install -r requirements.txt

It says the requirements are already satisfied. I'm guessing this is in reference to my local environment.

Requirement already satisfied (use --upgrade to upgrade): requests==2.7.0 in /Library/Python/2.7/site-packages (from -r requirements.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): beautifulsoup4==4.5.3 in /Library/Python/2.7/site-packages (from -r requirements.txt (line 2))

But if I try to run my Python script, I get a no module error:

Traceback (most recent call last): File "Webcrawler.py", line 3, in from urllib.request import urlopen ImportError: No module named request

Answer 1

I've solved it so:

1. I created (If there is not) the file "requirements.txt" directly into the root of the entrypoint (index.js, in my case)

2. I manually added the libraries with the specific versions into the file, in my case like this:

   requests==2.7.0
   beautifulsoup4==4.5.3
   

3. I created (If there is not) the file "runtime.txt" with with just one line: the python version i need, in my case:

   python-2.7.14
   

4. I created the multibuildpacks with the two commands:

   heroku buildpacks:set heroku/python
   heroku buildpacks:add --index 1 heroku/nodejs
   

5. Finally, I continued with the git commands:

   git add requirements.txt runtime.txt
   git commit requirements.txt runtime.txt -m "requirements"
   git push heroku master