incorrect `projectRoot` when using parcel in monorepo

🐛 bug report

I’m using lerna with yarn workspace just like you guys do. When I run parcel within a sub package, it can’t read the .env .proxyrc.js files inside the package, instead it reads them from the root of repo.

After digging into the code, turns out that projectRoot was set incorrectly, and there is no way to specify its value. Here is the code in @parcel/core

https://github.com/parcel-bundler/parcel/blob/v2/packages/core/core/src/resolveOptions.js#L52-L61

🎛 Configuration

with all default Configurations

🤔 Expected Behavior

parcel can reads configurations inside the sub package

😯 Current Behavior

parcel reads configurations from the root of repo

🔦 Context

possible solutions:

1. change parcel behavior in monorepo
2. add an option --project-root( projectRoot in API) to allow user to specify projectRoot

🌍 Your Environment

Software	Version(s)
Parcel	2.2.1
Node	v16.9.1
npm/Yarn	yarn 1.22.11 / npm 7.21.1
Operating System	macOS 12.1

[jpapini]

Adding an empty pnpm-lock.yaml (or any lockfile) file to a subpackage of the monorepo fakes the projectRoot directory of Parcel.

[mischnic]

Note that Parcel doesn’t watch anything outside the package root. So moving it somewhere inside of the monorepo will not watch other packages you might import from the monorepo.