Python and Node.js on Heroku

Question

I have started to make a Node server which runs on Heroku. It was working fine until I tried to use the (unofficial) Duolingo API. I wrote the following Python script to connect to the API:

import duolingo
import simplejson as json

lingo  = duolingo.Duolingo('harleyrowland')
print json.dumps(lingo.get_user_info())

and my Node server uses it using the following commands:

var python = require('python-shell');

module.exports = {
  getData: function(callback){
    python.run('duoScript.py', function (err, results) { 
      console.log(err);
      console.log(results);
      var res = JSON.parse(results);
      var language = res.language_data.es.language_string;
      var streak = res.language_data.es.streak;
      var level = res.language_data.es.level;
      var levelPerecentage = res.language_data.es.level_percent;
      var fluency = res.language_data.es.fluency_score;
      var nextLesson = res.language_data.es.next_lesson.skill_title;
      return callback({language, streak, level, levelPerecentage, fluency, nextLesson});
    });
  }
}

which all works totally fine locally.

When I pushed this to Heroku, the code didn't work and I started to get the following error in the Heroku logs:

{ [Error: ImportError: No module named duolingo]
     2016-10-06T00:02:32.133315+00:00 app[web.1]:   traceback: 'Traceback (most recent call last):\n  File "duoScript.py", line 1, in <module>\n    import duolingo\nImportError: No module named duolingo\n',
    executable: 'python',
    options: null,
    script: 'duoScript.py',
    args: null,
    exitCode: 1 
}

Because of this, I went on the Heroku API and found that I needed to add a requirements.txt file. So I did:

duolingo-api==0.3
simplejson==3.8.2

which still didn't work. I then found this answer and added a .buildpacks file:

https://github.com/heroku/heroku-buildpack-python.git
https://github.com/heroku/heroku-buildpack-nodejs.git

and I still get the same error.

Any idea what is causing this error?

Update 1

Thought I would show my Procfile too incase this was the problem:

web: node index.js
pipinstall: pip install -r requirements.txt

Update 2

Output of git push heroku master without pipinstall:

$ git push heroku master
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 288 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> Node.js app detected
remote: 
remote: -----> Creating runtime environment
remote:        
remote:        NPM_CONFIG_LOGLEVEL=error
remote:        NPM_CONFIG_PRODUCTION=true
remote:        NODE_ENV=production
remote:        NODE_MODULES_CACHE=true
remote: 
remote: -----> Installing binaries
remote:        engines.node (package.json):  5.9.1
remote:        engines.npm (package.json):   unspecified (use default)
remote:        
remote:        Downloading and installing node 5.9.1...
remote:        Using default npm version: 3.7.3
remote: 
remote: -----> Restoring cache
remote:        Loading 2 from cacheDirectories (default):
remote:        - node_modules
remote:        - bower_components (not cached - skipping)
remote: 
remote: -----> Building dependencies
remote:        Installing node modules (package.json)
remote: 
remote: -----> Caching build
remote:        Clearing previous node cache
remote:        Saving 2 cacheDirectories (default):
remote:        - node_modules
remote:        - bower_components (nothing to cache)
remote: 
remote: -----> Build succeeded!
remote:        ├── [email protected] extraneous
remote:        ├── [email protected] extraneous
remote:        ├── [email protected]
remote:        ├── [email protected]
remote:        ├── [email protected]
remote:        ├── [email protected]
remote:        ├── [email protected]
remote:        └── [email protected]
remote:        
remote: -----> Discovering process types
remote:        Procfile declares types -> web
remote: 
remote: -----> Compressing...
remote:        Done: 13M
remote: -----> Launching...
remote:        Released v25
remote:        https://arcane-anchorage-33274.herokuapp.com/ deployed to Heroku
remote: 
remote: Verifying deploy... done.

Answer 1

Maybe useful for some: if you are deploying via GitHub (and not via the Heroku CLI), you can add buildpacks for other languages in your Heroku dashboard under the Settings tab .