Hydra vs Xcode Cloud

Hydra is a continuous integration service for projects based on Nix. It checks out project source periodically or continuously, builds it, runs tests, and produces reports. Work is organized into jobsets whose inputs can trigger builds when they change; jobsets can also depend on one another. Flake jobsets are supported when their outputs expose a hydraJobs attribute set. Jobs can produce packages, ISO images, or tarballs, and jobset inputs can use Git checkout sources. Hydra also provides a JSON API. It is aimed at Nix and NixOS package developers, not people who only need to use NixOS. Hydra is open source under GPL-3.0 and listed at free. It is self-hosted, with no hosted option listed, and running it is currently supported only on NixOS; the repository recommends the NixOS module for production. Flake evaluation is restricted from accessing files outside the Nix store. Some state is stored in the database, so backups are needed, and the wiki reports that hydra-queue-runner can sometimes leave queued builds unscheduled.

Xcode Cloud is a freemium continuous integration and delivery service built into Xcode for Apple developers. It builds committed code changes and runs automated tests in parallel using cloud resources. Teams can customize workflows or begin with a built-in workflow. Xcode shows build and test results, live status, and user crash feedback, while App Store Connect displays build and test information and lets teams edit workflows or launch builds. Builds can be delivered to team members and selected external testers through TestFlight. Source repositories may be hosted on Bitbucket, GitHub, or GitLab, including supported self-hosted versions. Apple says builds use temporary isolated environments, source code is not persisted, credentials are not directly exposed to build environments, and data is encrypted in transit and at rest. Use requires Apple Developer Program membership, Xcode 15 or later, and a remote Git repository. Plans include 25 compute hours monthly at free, 100 hours for $49.99 a month, 250 for $99.99 a month, 1000 for $399.99 a month, and 10000 for $3,999.99 a month. Unused hours do not roll over.