[Hydra - NixOS Wiki](https://nixos.wiki/wiki/Hydra) is an open-source continuous integration (CI) system developed by the NixOS community. It provides a platform for building, testing, and deploying software projects. [[NixOS]], on the other hand, is a purely functional Linux distribution built around the Nix package manager. Hydra plays a crucial role in the development and maintenance of NixOS. It allows developers to continuously integrate changes made to the NixOS codebase by automatically building and testing them across various platforms and configurations. This helps ensure that every change made to NixOS is thoroughly tested and does not introduce any regressions or issues. By leveraging Hydra, the NixOS community can achieve a high degree of automation in their development process. This reduces manual effort, accelerates feedback loops, and improves overall productivity. Hydra also provides a centralized platform for managing different stages of software development, including building, testing, staging, and deployment. On the other hand, NixOS benefits Hydra through its unique approach to package management and system configuration. NixOS uses a declarative approach where system packages and configurations are defined in a reproducible manner using Nix expressions. This ensures that all dependencies are explicitly specified and isolated from each other. NixOS's declarative nature aligns well with Hydra's goal of providing reproducible build environments. The combination allows Hydra to easily manage complex build configurations across multiple platforms without conflicts or inconsistencies. Additionally, as Hydra builds upon the Nix package manager, it inherits its powerful features such as atomic upgrades/rollbacks, transactional updates, and dependency management. These features enhance the reliability and stability of Hydra's CI infrastructure. In summary, Hydra and NixOS have a symbiotic relationship where they mutually benefit each other's growth. Hydra provides automated building and testing capabilities for NixOS development while leveraging NixOS's declarative package management approach. Together they create a powerful CI system that helps ensure the quality and reliability of the NixOS distribution. # References ```dataview Table title as Title, authors as Authors where contains(subject, "Hydra") sort title, authors, modified ```