# \[no-LLM\] \`nix-weather-hs\` - analyzing un-built derivation graphs for cache availablility

DevFeed: [\[no-LLM\] \`nix-weather-hs\` - analyzing un-built derivation graphs for cache availablility](<https://devfeed.tech/articles/no-llm-nix-weather-hs-analyzing-un-built-derivation-graphs-for-cache-availablility-31360.md>)

Original publisher: [Read original article](<https://discourse.nixos.org/t/no-llm-nix-weather-hs-analyzing-un-built-derivation-graphs-for-cache-availablility/79113>)

Author: MagicRB

Published: 2026-07-22T18:52:23Z

Content type: article

Language: en

Sources: [Announcements - NixOS Discourse](<https://devfeed.tech/sources/announcements-nixos-discourse.md>)

Topics: [Nix](<https://devfeed.tech/topics/nix.md>), [Caching](<https://devfeed.tech/topics/caching.md>), [Graphs](<https://devfeed.tech/topics/graphs.md>), [configuration](<https://devfeed.tech/topics/configuration.md>)

Tags: [announcements](<https://devfeed.tech/tags/announcements.md>), [build](<https://devfeed.tech/tags/build.md>), [cache](<https://devfeed.tech/tags/cache.md>), [configuration](<https://devfeed.tech/tags/configuration.md>), [graphs](<https://devfeed.tech/tags/graphs.md>)

## AI overview

A forum post announces the first functional version of nix-weather-hs, a Nix project that checks cache availability across a derivation closure, builds an in-memory graph, and exports it in multiple formats. It is designed to help debug derivations that cannot be built because of resource limits or other reasons.

## Source excerpt

no artificial intelligence, only human stupidity (specifically mine) Hey everyone, I am hereby announcing the first functional version of nix-weather-hs. This project is inspired and based on nix-weather by @cafkafk. For details see the README.org, but the brief version is that nix-weather-hs will check cache availability for a whole closure, build a graph in memory and then it allows you to export said graph into multiple formats. Before export there are a few filters available, which make the resulting graphs more readable. As an example you can use the following command to check the availability of a NixOS configuration, reduce the graph to the 2nd level leaves of the uncached portion. nix-weather-hs graph --filter 'uncached' --filter 'leaves@2' --output dot $(nix eval --raw .#nixosConfigurations.nixos.config.system.build.toplevel.drvPath) As you can see, nix-weather-hs currently works with derivations, which is a defining feature compared to nix-weather. My version was specifically built to debug cases, where you are unable to even built the derivation, due to resource limits or other reasons. If you want to contribute, open issues, you should be able to log into my Forgejo with GitHub (codeberg planned). If any issues arise, please ping me. If you want to reach out privately, to talk about, well anything, please don't hesitate to contact me here, on matrix @magic_rb:matrix.redalder.org or Signal magic_rb.01. If you're considering asking an LLM a question about this project, please ask me instead. Thank you for your time and hopefully nix-weather-hs is useful to you. 27 posts - 4 participants Read full topic