This is an Heroku buildpack supporting deployment of Node.js applications within a monorepo, where the application might make use of shared resources outside its subdirectory tree within the monorepo.
This is based on the example of
Heroku Multi Procfile buildpack,
extending that to include the copying of the application's package.json and package-lock.json
files to Heroku's root application compilation directory.
The buildpack expects to find an environment variable, APP_BASE, which points to the
relative path of the application directory within the monorepo.
It also expects to find the Procfile, package.json, and package-lock.json
files within the APP_BASE directory.
The Procfile should look like this where $APP_BASE points to appdir:
web: cd appdir && node path/to/app-start.js