Hydra vs Prow
Hydra
github.comProw
docs.prow.k8s.ioSide by side
| Figure | Hydra | Prow |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | Yes | — |
| Web | Yes | Yes |
| Linux | Yes | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 1 |
| Spec score · Continuous Integration Software | 8.5 (#11) | 7.6 (#36) |
| API | The repository includes a JSON API specification in hydra-api.yaml and points users to Swagger Editor for exploration. | The optional Gangway component exposes gRPC endpoints to create jobs and get or list job executions. |
| Deployment | The repository says running Hydra is currently only supported on NixOS and recommends the NixOS module for production. | Prow runs in Kubernetes clusters, and the deployment guide says it should work on any Kubernetes distribution with no or minimal changes. |
| Integrations | Hydra jobset inputs can use Git checkout sources, and the documented examples use GitHub repositories. | Prow integrates with GitHub and can also work with Gerrit, though Tide and Hook do not work with Gerrit. |
| Purpose | Hydra is a continuous integration service for Nix based projects. | Prow is a Kubernetes based CI/CD system for running jobs and automating GitHub workflows. |
Plans
In their own words
Hydra
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.