Gradient

Nix-CI for Teams. Every flake built once, on any machine, cached for everyone.

🚀 Quick Start • 📖 Documentation • 🌐 Public Instance • 🔍 Options Search • 💬 Matrix Chat •

📸 Screenshot Gallery

https://github.com/user-attachments/assets/bd733d97-fd8b-4439-b880-04387ba1e073

Gradient evaluates and builds Nix flakes on a pool of workers, starts builds while the evaluation is still running and serves every result from a built-in binary cache.

Features

CLI

Download Gradient CLI: a static Linux binary, no Nix needed. Build uncommitted changes on the CI workers:

# Install Gradient
curl -fLo gradient "https://public.gradient.ci/api/v1/tasks/gradient/main/entry-point-downloads?eval=packages.x86_64-linux.gradient-cli-static&filename=gradient"
chmod +x gradient && sudo mv gradient /usr/local/bin/
# or via Nix: nix run github:wavelens/gradient/latest#gradient-cli-full -- [flags]

gradient login https://gradient.example.com
gradient build .#hello

All commands: CLI Reference.

Compared to Hydra and GitHub Actions

	Hydra	GitHub Actions + Cachix	Gradient
Build start	After the whole evaluation	After the whole evaluation	While the evaluation is still running
Evaluation	On the server, limited by one machine	Inside each job, limited by the runner	On workers, scales with them
Evaluation speed	Fast	Slow	Fastest available
Building Order	Round Robin	single Worker	Maximum CPU Load, Minimal Network Traffic, Memory / OOM aware
Import from derivation (IFD)	Not activly supported	Built by the runner inside the job	Built on the workers as shared builds, cached and logged like any build
Wildcard Support	No	No	Yes
Nix store	Kept on the server and builders	Empty on every job; each job downloads its closure again	Kept on the workers between builds
Build outputs	Everything through the server	Pushed from the runner to Cachix	Large outputs go from worker straight to S3
Server host	Needs a writable Nix store	Hosted by GitHub	Needs no Nix store, Micro-VM ready
Heavy builds	Static machine list with speed factors	Fixed runner sizes	Scoring system places them by predicted memory, learned from past builds
Remote building over SSH	Not available	Not available	ssh-ng:// store for nixos-rebuild --build-host and nix copy straight to the CI workers
Private caches	One store for the whole instance	Free plan: 5 GB, filled quickly by full closures	Per-project caches with access control, on own S3 or disk storage
Sign-in	Local accounts, LDAP, OIDC with roles for the whole instance	GitHub accounts	OIDC with provider groups mapped to roles per project, SCIM provisioning
Integrations	Minimal JSON API	GitHub only	REST API, webhooks, Git Integrations and MCP server
Web UI	Server-rendered pages	GitHub job logs	Responsive UI with live log streaming
Runners	Not available	builtin	Soon; On Roadmap
Stars		-

Installation

A NixOS module sets up the server, a local worker, PostgreSQL and the reverse proxy. The Quick Start walks through the setup in three steps.

For a first try on a personal repository, the Standalone instance is running everything in one container or VM:

docker run -dt --name gradient --privileged --cgroupns=host -p 127.0.0.1:8080:80 -v gradient:/var/lib ghcr.io/wavelens/gradient-standalone
# or
nix run github:wavelens/gradient/latest#standalone

Pre-built Gradient packages:

URL:        https://public.gradient.ci/cache/main
Public Key: public.gradient.ci-main:qmxRE+saUvhNa3jqaCMWje+feVU77TjABchZrPGf7A8=

API

A REST API backs the web UI and the CLI: OpenAPI spec, Swagger UI.

Roadmap

Planned releases in the Roadmap. Feedback in GitHub Discussions or on Matrix.

Contributing

Contributions are welcome: see the Contributing Guidelines and the Contributor Docs.

Project

• Support: community help, long-term and commercial support.
• Security Policy: private vulnerability reports.
• Privacy: no telemetry, all data self-hosted.
• Governance: roles, maintainers and decisions.
• Accessibility: web UI support and barrier reports.

License

AGPL-3.0-only, with license notices following the REUSE guidelines. Developed by Wavelens GmbH.