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

gradient_test_10mb.mp4

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

Git Host Integration	GitHub, Gitea / Forgejo and GitLab: builds on push and pull request. Sends status checks back
Build Before Pushing	Uncommitted changes built on the CI workers with gradient build
Built-in Binary Cache	Per-project caches with S3 storage, signing and sharing between projects
Scales With Workers	Evaluation and builds both run on workers; each added machine adds capacity
MCP Server	Failed builds, logs and evaluations, readable by any AI assistant
Pull Deployment	Machines fetch and switch to their latest built NixOS configuration on their own
Declarative Setup	Users, projects, caches and workers as NixOS options, validated at build time
SSO and Teams	OIDC login, SCIM provisioning, roles and invites per project and cache

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 finishes	After the job has evaluated the flake	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
Import from derivation (IFD)	Not supported	Built by the runner inside the job	Built on the workers as shared builds, cached and logged like any build
Nix store	Kept on the server and builders	Empty on every job; each job downloads its closure again	Kept on the workers between builds
Shared work	One build per derivation	Parallel jobs can build the same derivation twice	Every derivation built once, shared across projects
Build outputs	Pass 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, fits in a micro-VM
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	Only outbound, to its own build machines	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
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.