install-nix-action

Installs Nix on GitHub Actions for the supported platforms: Linux and macOS.

By default it has no nixpkgs configured, you have to set nix_path by picking a channel or pin nixpkgs yourself (see also pinning tutorial).

Features

• Quick installation (~4s on Linux, ~20s on macOS)
• Multi-User installation (with sandboxing enabled only on Linux)
• Self-hosted github runner support
• Allows specifying Nix installation URL via install_url
• Allows specifying extra Nix configration options via extra_nix_config
• Allows specifying $NIX_PATH and channels via nix_path
• Share /nix/store between builds using cachix-action for simple binary cache setup to speed up your builds and share binaries with your team

Usage

Create .github/workflows/test.yml in your repo with the following contents:

name: "Test"
on:
  pull_request:
  push:
jobs:
  tests:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2.3.4
    - uses: cachix/install-nix-action@v12
      with:
        nix_path: nixpkgs=channel:nixos-unstable
    - run: nix-build

Usage with Flakes

name: "Test"
on:
  pull_request:
  push:
jobs:
  tests:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
      with:
          # Nix Flakes doesn't work on shallow clones
          fetch-depth: 0
    - uses: cachix/install-nix-action@v12
      with:
        install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-3.0pre20200820_4d77513/install
        extra_nix_config: |
          experimental-features = nix-command flakes          
    - run: nix-build

Inputs (specify using with:)

• install_url: specify URL to install Nix from (useful for testing non-stable releases or pinning Nix for example https://releases.nixos.org/nix/nix-2.3.7/install)

• nix_path: set NIX_PATH environment variable, for example nixpkgs=channel:nixos-unstable

• extra_nix_config: append to /etc/nix/nix.conf

---

FAQ

Is it possible to run NixOS tests / Qemu+KVM with GitHub Actions?

Currently GitHub Actions are not running on Azure instance types that support nested virtualization.

How do I print nixpkgs version I have configured?

nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'

How can I run NixOS tests?

With the following inputs:

    - uses: cachix/install-nix-action@vXX
      with:
        extra_nix_config: "system-features = nixos-test benchmark big-parallel kvm"

Note that there's no hardware acceleration on GitHub Actions.

How can I install packages via nix-env from the specified nix_path?

nix-env -i mypackage -f '<nixpkgs>'

Hacking

Install the dependencies

$ yarn install

Build the typescript

$ yarn build

Run the tests ✔️

$ yarn test