GitHub Action - Upload release.nix

Problem

Your repository includes Nix expressions that depend on submodules. GitHub source archives do not include submodules, so you need a clone of the repository to import the expressions.

Solution

Upload a release.nix lock file for each release, containing the revision and the hash, so that you can use fetchgit to clone the repository with submodules and import expressions.

Usage

Create a GitHub Actions workflow triggered on the creation of releases. The job should check out the repository, install Nix, and use this action:

name: "Release"
on:
  release:
    types:
      - created

jobs:
  nix-release:
    runs-on: ubuntu-latest
    steps:
      - name: Check out code
        uses: actions/checkout@v2.3.4
        with:
          submodules: recursive

      - name: Install Nix
        uses: cachix/install-nix-action@v12

      - name: Upload release.nix
        uses: ttuegel/upload-release.nix@v1.0
        with:
          token: ${{ secrets.GITHUB_TOKEN }}