Which failing packages are responsible for the most downstream breakage?

Does there exist any tool in the nixpkgs ecosystem that can rank order derivations that are currently failing or broken on hydra by how many packages they break?

i.e. if a very common / foundational package is broken which is thus causing all of its downstream packages to break, that package should come first in such a list.

Also very interested in this for evaluating the state of Darwin packaging, and have begun working on a python based tool for evaluating broken nixpkgs cross referenced with hydra build failures.

@mjlbach: does the hydra API expose sufficient information to compute this?

Yes, I believe so. Here is how hydra-check uses it: https://github.com/nix-community/hydra-check/blob/4b60c03fb43c78eca6a241384f3a50b36863d911/hydracheck/cli.py#L78

It’s probably not a good idea to hit hydra with a bunch of calls though.

you can point GitHub - nix-community/nix-review-tools: WIP tooling [maintainer=@samueldr] at a hydra evaluation, and it will do what you want. I usually do:

mkdir tmp
cd tmp
../eval-report $hydra_num > index.html
xdg-open index.html

It will order them by downstream failures

Perfect. Thanks, @jonringer!