nix-installer

Install Nix - works on GitHub-hosted runners, self-hosted runners, and inside containers.

With FlakeCache binary cache enabled by default for faster builds!

Features

• ✅ Smart detection - Skips install if Nix already present (container mode)
• ✅ Flakes enabled - nix-command and flakes enabled by default
• ✅ Universal - Works on ubuntu-latest, self-hosted, and nixos/nix containers
• ✅ Fast - No install needed when using containers
• 🚀 FlakeCache - Binary cache enabled by default for faster builds

Usage

Basic (with FlakeCache)

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: FlakeCache/nix-installer@v1
      - run: nix build

With Container (Fastest on self-hosted)

jobs:
  build:
    runs-on: self-hosted
    container: nixos/nix:latest
    steps:
      - uses: actions/checkout@v4
      - uses: FlakeCache/nix-installer@v1
      - run: nix build

Disable FlakeCache

- uses: FlakeCache/nix-installer@v1
  with:
    flakecache: 'false'

Add Extra Binary Caches

- uses: FlakeCache/nix-installer@v1
  with:
    extra-substituters: 'https://nix-community.cachix.org'
    extra-trusted-keys: 'nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs='

Universal Matrix (Same workflow for all runner types)

jobs:
  build:
    strategy:
      matrix:
        include:
          - runner: self-hosted
            container: nixos/nix:latest
          - runner: ubuntu-latest
            container: nixos/nix:latest
          - runner: ubuntu-latest
            container: ''
    runs-on: ${{ matrix.runner }}
    container: ${{ matrix.container || null }}
    steps:
      - uses: actions/checkout@v4
      - uses: FlakeCache/nix-installer@v1
      - run: nix build

Inputs

Input	Description	Default
flakecache	Enable FlakeCache binary cache	true
install-cli	Install FlakeCache CLI for push/pull	false
cli-version	FlakeCache CLI version	latest
extra-substituters	Additional binary cache URLs (space-separated)	''
extra-trusted-keys	Additional trusted public keys (space-separated)	''
extra-conf	Extra lines to add to nix.conf	''

Outputs

Output	Description
nix-path	Path to the Nix binary
already-installed	true if Nix was already installed (container mode)
cli-path	Path to FlakeCache CLI (if installed)

Binary Caches

By default, this action configures:

Cache	URL	Priority
FlakeCache	https://c.flakecache.com	1st (fastest)
NixOS	https://cache.nixos.org	2nd (fallback)

Push to Cache (with CLI)

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: FlakeCache/nix-installer@v1
        with:
          install-cli: 'true'
      - run: nix build
      - name: Push to FlakeCache
        run: flakecache push ./result
        env:
          FLAKECACHE_TOKEN: ${{ secrets.FLAKECACHE_TOKEN }}

How It Works

1. Detects if Nix is already installed (e.g., in nixos/nix container)
2. Skips installation if already present
3. Installs Nix if not found (using official installer)
4. Configures flakes, FlakeCache, and experimental features
5. Adds any extra caches/configuration you provide

License

MIT