Unofficial Heroku buildpack: Python + npm dependency resolution

This is a Heroku buildpack for Python apps. It uses virtualenv and pip.

Differences

The main difference from the official Python buildpack is support for node dependencies via npm.

This is accomplished via an npm_requirements.txt which must be in the base directory (along with the requirements.txt file that is used by pip)

If an npm_requirements.txt file is present it works similar to the way you're used to with pip.

Each line of the file is appended to npm install so for example

npm_requirements.txt:

coffee-script
less@1.0.0

would result in the following commands being run to resolve the dependencies:

$ npm install -g coffee-script
$ npm install -g less@1.0.0

Why install Node along with Python?

Primarily because it's desirable to use technologies like less-css and coffeescript on the server (with something like django compressor for example)

Usage

Example usage:

$ ls
Procfile  requirements.txt  web.py

$ heroku create --stack cedar --buildpack git@github.com:jiaaro/heroku-buildpack-django.git

$ git push heroku master
...
-----> Heroku receiving push
-----> Fetching custom build pack... done
-----> Python app detected
-----> Preparing virtualenv version 1.6.4
       New python executable in ./bin/python
       Installing setuptools............done.
       Installing pip...............done.
-----> Installing dependencies using pip version 1.0.2
       Downloading/unpacking Flask==0.7.2 (from -r requirements.txt (line 1))
       Downloading/unpacking Werkzeug>=0.6.1 (from Flask==0.7.2->-r requirements.txt (line 1))
       Downloading/unpacking Jinja2>=2.4 (from Flask==0.7.2->-r requirements.txt (line 1))
       Installing collected packages: Flask, Werkzeug, Jinja2
       Successfully installed Flask Werkzeug Jinja2
       Cleaning up...

The buildpack will detect your app as Python if it has the file requirements.txt in the root. It will detect your app as Python/Django if there is an additional settings.py in a project subdirectory.

It will use virtualenv and pip to install your dependencies, vendoring a copy of the Python runtime into your slug. The bin/, include/ and lib/ directories will be cached between builds to allow for faster pip install time.

Hacking

To use this buildpack, fork it on Github. Push up changes to your fork, then create a test app with --buildpack <your-github-url> and push to it.

To change the vendored virtualenv, unpack the desired version to the src/ folder, and update the virtualenv() function in bin/compile to prepend the virtualenv module directory to the path. The virtualenv release vendors its own versions of pip and setuptools.

Changing Buildpacks

If you've already deployed an app to heroku and you'd like to switch to this buildpack from the standard python buildpack, just run the following command with the heroku command line app:

heroku config:add BUILDPACK_URL=git://github.com/jiaaro/heroku-buildpack-django.git