# NixOS/hydra

Hydra, the Nix-based continuous build system [maintainers=@dasj,@Ericson2314]

Repository: https://github.com/NixOS/hydra
Canonical: https://ross.abutalabs.com/products/nixos-hydra
Homepage: http://nixos.org/hydra
Language: PLpgSQL
License: GPL-3.0
License Family: copyleft
Topics: cicd, nixos
Last push: 2026-08-26T13:50:06+00:00

## Health v2 (maintenance only)
Score: 77/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 35, longevity 100
- inputs: {"age_days": 5423, "days_push": 7, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1558, forks 356 (observed 2026-08-28T04:05:03.236101+00:00)

## What it is
Hydra is the Nix-based continuous integration and build farm service from the NixOS project. It evaluates Nix expressions to schedule, run, and publish builds across a cluster of build machines, with a web UI and REST API.

## Use cases
- set up a self-hosted CI server for Nix projects
- build and cache Nix packages automatically on every commit
- run a distributed build farm for nixpkgs
- publish build artifacts and release binaries from Nix expressions
- track build status and failures across many jobsets

## When to choose
- your project uses Nix or NixOS and you want reproducible CI builds
- you need a self-hosted build farm with Nix-native evaluation
- you want to produce binary caches from CI builds

## When to avoid
- your project does not use Nix and you want a general-purpose CI system
- you need a hosted SaaS CI solution
- you cannot run NixOS, since Hydra is primarily supported on NixOS

## Facets
- artifact type: service
- maturity: active
- function: ci-cd, build-tool, http-server, deployment
- domain: developer-tools, self-hosted
- platform: self-hosted
- tags: nix, continuous-integration, build-farm, nixos, self-hosted-ci, devops, linux, web-server

## Member repositories
- NixOS/hydra (main) score 77

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:03.236101+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:29:52.735082+00:00, confidence not recorded.
  - readme: https://github.com/NixOS/hydra (fetched 2026-08-28T04:05:03.236101+00:00, sha 62adaf0e4c31)
  - homepage: http://nixos.org/hydra (fetched 2026-08-29T11:29:41.204868+00:00, sha 5362f1e6a0a3)
- Data as of 2026-08-30T08:39:29.467469+00:00.