How to get Heroku to recognize a yarn.lock or package.json within a subdirectory (not root)

Question

I have a Rails application using React, Webpack, and Yarn for the client side. I have everything relating to the client side within the /client directory. This includes my yarn.

Answer 1

I'll add an answer for document another possible use-case. I experienced something similar, multiple buildpacks and I had checked everything in all answers:

• node-js was declared first in .buildpacks file
• a yarn.lock was added in the root of the project
• yarn dependency declared under engines on package.json

Nevertheless yarn was not picking up since I was using an older version of node-js buildpack.

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Bumping the version of the buildpack the latest solve my problem:

https://github.com/heroku/heroku-buildpack-nodejs#v118