[RFC] Tags and scopes (enforce module boundaries)

[haukurmar]

Which project is this feature idea for?

Turborepo

Describe the feature you'd like to request

When you are building a mono-repo you want to avoid having circular dependencies between packages, so you would like to define what packages can import other packages.

NX has a good way of doing this with what they call module boundaries using tags and scopes define in the project.json, then the linter takes over.

https://nx.dev/core-features/enforce-module-boundaries

an example of this would look something like this.

app: web
package: ui
package: config
package: auth

The app "web" imports on all of these packages
The package "ui" should not be able to import from any of these since it's stand-alone
The package "auth" can reference "config", but not ui or web.

I hope this explains it a bit, otherwise you can look into how NX is doing it.

Describe the solution you'd like

I am not sure how this should be implemented, perhaps an inspiration from NX and how they solve it.

It would be nice that this could be configured in a turbo.json inside each package and/or on the root of the workspace.

Describe alternatives you've considered

Alternative is to use NX as it provides this feature and a lot more.

[NicholasLYang]

Hey @haukurmar, thanks for the suggestion! I'll add it to our list of potential features. We're definitely making ergonomics and observability a top priority, and this feature seems to fall under those categories.

[austinbiggs]

I'd like to echo the benefits of module boundaries. I'm pretty eager to migrate my Nx monorepo to Turborepo, but losing the guardrails that help to prevent circular dependencies is a turn off.

[anthonyshew]

Minor note: Turborepo always errors on circular dependencies so that specific concern is taken care of today. 👍

(There's certainly still a ton of value to be added by a true module boundary enforcement feature - but just to speak to that concern in particular!)

[haukurmar]

Can you elaborate a bit more?
I am using Turborepo in one of my projects and I know of many circular dependencies between packages and I see no errors.

[kaoz70]

I have been using Turborepo (with Yarn classic or pnpm) and I have not seen Turborepo error on this, could you explain where this happens? Maybe I am missing something.

[donnellyjoe]

I was looking at nx recently and got jealous of the tags/lint feature. I then found this ESLint plugin which has similar functionality. I don't love how it is configured by pattern matching against paths to packages though. Adding/removing/renaming packages would require manually updating the lint configuration. I would love to see something like this implemented directly within turbo, but I'm not exactly what the ergonomics of it would look like