Using a Node module in a Django / Python app on Heroku

Question

I have a fairly classic Python/Django app deployed to Heroku.

There's a pip package I want to use, django-mjml that itself relies on a Node.js module named mjml.

My question is how to combine the two? Doing npm init and npm install mjml created a node_modules directory in my root folder, and also the files: package.json and package-lock.json. I guess that's not really what I want?

Not sure how to proceed from here and any directions are appreciated!

Answer 1

I haven't used that library, but you probably need to use multiple buildpacks:

1. Set your main buildpack to heroku/python:

   heroku buildpacks:set heroku/python
   

2. Add the heroku/nodejs buildpack:

   heroku buildpacks:add --index 1 heroku/nodejs
   

3. Confirm that the Node.js buildpack will run first and the Python buildpack will run second with

   heroku buildpacks
   

Make sure you've got

• a requirements.txt file (if you're using pip) or both Pipfile and Pipfile.lock (if you're using Pipenv) committed for your Python dependencies, and
• a package.json file and either package-lock.json (if you're using npm) or yarn.lock (if you're usng Yarn) committed for the mjml dependency.

The package.json and package-lock.json you mention in your question should suffice for the Node.js dependencies, but they have to be committed, and you need to set the buildpacks before pushing.