Allow an affected target to run only on directly modified projects without walking the dependency graph

[meDavidNS]

• I'd be willing to implement this feature (contributing guide)

Description

I would like to execute a target on all directly affected projects in the nx workspace. My usecase is specifically for linting, but could be usefull for formatting or docs generation as well.

Motivation

For linting I would like to run the target only on directly affected projects, unlike unit tests or e2e tests, reducing the amount of time required to run nx affected -t lint. For linting it doesn't make sense to walk the dependency trying to executing the same target on other projects that depend on the directly modified project.

Suggested Implementation

For the nx affected command implement a --direct or --depth option.

Please let me know if you would welcome a PR.

[FrozenPandaz]

For lint in particular, it's generally not the slowest part of the pipeline so it's less important. If the lint tasks do not have any inputs which start with ^ though they will run, they would be cached. This is how the lint tasks are configured by default.

If we were to add something we would need to design it out further.

[meDavidNS]

My case might be a bit different. I use nx-go and linting in Go is considerably slower.

[meDavidNS]

Even with out frontend pipeline this takes multi-minute to lint around 170 projects in our repository, most of the time being taken by tailwind plugins for eslint.

[AndreasHerz]

Same issue here 👋🏼
We would like to only publish directly affected projects to SonarCloud.
Dependencies don't matter…

[MattCCC]

+1. We ended up with a custom script and we're considering removal of nx because of that actually. If we still need a custom solution to check for dependencies then it's much less useful than we thought at the beginning. A pity.

[TheWallOfDucks]

Yeah we are in the exact same scenario using NX to publish results to SonarCloud...we end up having to publish results for lots of code that hasn't even changed.

[MattCCC]

What we did is basically a small node script that does git diff to take files and then we use nx affected with --files flag. Works like a charm. I still think it's something that nx affected should be doing out of the box.

[TheWallOfDucks]

Thanks for the idea @MattCCC . Sounds like that could work for my scenario too, but agree it's a shame it's not something available out of the box.

[chrismayverantos]

for precommit checks were doing something like this:
npx nx affected:lint --files="$(git diff --cached --name-only -z | tr '\0' '\n' | paste -sd ',' -)"

[meDavidNS]

That would still run the lint target for all the projects that have a dependency on the projects that are touched by the git diff, if I'm not mistaken? I think it would require manually filtering the nx graph structure to achieve only the directly affected projects.

[MattCCC]

That would still run the lint target for all the projects that have a dependency on the projects that are touched by the git diff, if I'm not mistaken? I think it would require manually filtering the nx graph structure to achieve only the directly affected projects.

Yes, you are right. You would be much better off with a custom node script or an nx plugin instead. Git diff is the solution but you cannot combine it with affected. More likely with nx run-many.