nix-profile-action

A GitHub Action to install Nix packages into an ephemeral profile.

The action is particularly useful if you use a self-hosted GitHub Actions Runner on NixOS. Third-party actions frequently require certain tools to be installed which are by default not available to the runner. With this action, you can install Nix packages easily making them available to following actions.

As soon as the action terminates—no matter if successfully or unsuccessfully—the profile is purged to allow garbage collection of all installed derivations.

Usage

Install packages by giving a comma-separated string of packages from a flake. If no flake reference is given, nixpkgs from the checked out repository's flake is assumed. Example:

name: 'nix-profile-action packages'
on:
  - pull_request
  - push
jobs:
  tests:
    runs-on: self-hosted
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          fetch-depth: 0
      - uses: yaxitech/nix-profile-action@v1
        with:
          packages: "nixpkgs#hello, figlet"
      - run: |
          hello
          figlet "Hello nix-profile-action!"

On some occasions, you need to compose a custom derivation from a Nix expression, for example, to install Python 3 with specific packages. This can be done with the expr input. The action evaluates the passed string through nix profile install --expr. Within your expression, nixpkgs from the checked out repository's flake is available as pkgs, while the repository's flake itself is available as repoFlake. Example:

name: 'nix-profile-action expr'
on:
  - pull_request
  - push
jobs:
  tests:
    runs-on: self-hosted
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          fetch-depth: 0
      - uses: yaxitech/nix-profile-action@v1
        with:
          expr: 'pkgs.python3.withPackages(ps: with ps; [toml pyyaml])'
      - run: |
          python3 ...

Prerequisites

This action requires a Flake-enabled Nix with support for profiles.

NixOS

{
  nix = {
    package = pkgs.nixFlakes;
    extraOptions = ''
      experimental-features = nix-command flakes ca-references
    '';
  };
}

Non-NixOS

Use cachix/install-nix-action to install Nix with flake support. Make sure you also add ca-references to the input extra_nix_config:

extra_nix_config: |
  experimental-features = nix-command flakes ca-references

Development notes

After you changed package.json, you also need to refresh the Nix packages in node-env. You can do so by first deleting the node_modules directory and then run (in the top-level directory): nix run .#refresh-node-env.

Some of the TypeScript tests invoke nix during test execution. That means if you invoke the tests through nix, for example as part of nix build, a nix that has the recursive-nix feature enabled is required. You can put the following snippet into your configuration.nix: