nix.yml

name: Nix

on:
  push:
    branches:
      - main
    paths:
      - '.github/workflows/nix.yml'
      - 'flake.*'
      - 'setup.cfg'
      - '*.nix'
      - '*.py'
      - '*.ini'
  pull_request:
    paths:
      - '.github/workflows/nix.yml'
      - 'flake.*'
      - 'setup.cfg'
      - '*.nix'
      - '*.py'
      - '*.ini'

jobs:
  check:
    runs-on: ubuntu-22.04
    outputs:
      NIXPKGS: ${{ steps.prep.outputs.NIXPKGS }}
      NIX_PATH: ${{ steps.prep.outputs.NIX_PATH }}
    env:
      nixpkgs: nixos-24_11
    steps:
      - name: Checkout
        id: checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          fetch-tags: true

      - name: Install nix
        id: install_nix
        uses: nixbuild/nix-quick-install-action@v28

      - name: Show the flake
        id: show
        run: |
          nix flake show

      - name: Check the flake
        id: check
        env:
          # FIXME: Our python39 package depends on some broken zope
          NIXPKGS_ALLOW_BROKEN: 1
        run: |
          echo FIXME: nix flake check --impure

      - name: Restore and cache Nix store for nixpkgs-${{ env.nixpkgs }}
        uses: nix-community/cache-nix-action@v5
        with:
          # restore and save a cache using this key
          primary-key: nixpkgs-${{ env.nixpkgs }}-${{ hashFiles('flake.*', '*.nix') }}
          # if there's no cache hit, restore a cache by this prefix
          restore-prefixes-first-match: nixpkgs-${{ env.nixpkgs }}-
          # collect garbage until Nix store size (in bytes) is at most this number
          # before trying to save a new cache
          gc-max-store-size-linux: 1073741824
          # do purge caches
          purge: true
          # purge all versions of the cache
          purge-prefixes: nixpkgs-${{ env.nixpkgs }}-
          # created more than 0 seconds ago relative to the start of the `Post Restore` phase
          purge-created: 0
          # except the version with the `primary-key`, if it exists
          purge-primary-key: never

      - name: Prepare environment
        id: prep
        run: |
          # Get the reference to the nixpkgs pinned in the flake - dirty way
          NIXPKGS=$(nix flake metadata | grep -E '[^\w]+nixpkgs-${{ matrix.nixpkgs }}[^\w]+:' | cut -d' ' -f2 | cut -d'?' -f1)
          NIX_PATH=nixpkgs=https://github.com/NixOS/nixpkgs/archive/${NIXPKGS##*/}.tar.gz
          # Pass those variables to the next steps and jobs
          echo NIXPKGS=$NIXPKGS | tee -a $GITHUB_ENV >> $GITHUB_OUTPUT
          echo NIX_PATH=$NIX_PATH | tee -a $GITHUB_ENV >> $GITHUB_OUTPUT

      - name: Generate version
        # The Nix package doesn't know how to do this part, unfortunately.
        run: |
          nix-shell \
            -p 'python3.withPackages (ps: [ ps.setuptools ])' \
            --run 'python setup.py update_version'

  packaging:
    runs-on: ubuntu-22.04
    needs: check
    env:
      NIXPKGS: ${{ needs.check.outputs.NIXPKGS }}
      NIX_PATH: ${{ needs.check.outputs.NIX_PATH }}
    strategy:
      fail-fast: false
      matrix:
        python-version:
          - 310
          - 311
        nixpkgs:
          - nixos-24_11
    steps:
      - name: Checkout
        id: checkout
        uses: actions/checkout@v4

      - name: Install nix
        id: install_nix
        uses: nixbuild/nix-quick-install-action@v28

      - name: Restore and cache Nix store for nixpkgs-${{ matrix.nixpkgs }}
        uses: nix-community/cache-nix-action@v5
        with:
          # restore and save a cache using this key
          primary-key: python${{ matrix.python-version }}-nixpkgs-${{ matrix.nixpkgs }}-${{ hashFiles('flake.*', '*.nix') }}
          # if there's no cache hit, restore a cache by this prefix
          restore-prefixes-first-match: nixpkgs-${{ matrix.nixpkgs }}-
          # collect garbage until Nix store size (in bytes) is at most this number
          # before trying to save a new cache
          gc-max-store-size-linux: 1073741824
          # do purge caches
          purge: true
          # purge all versions of the cache
          purge-prefixes: python${{ matrix.python-version }}-nixpkgs-${{ matrix.nixpkgs }}-
          # created more than 0 seconds ago relative to the start of the `Post Restore` phase
          purge-created: 0
          # except the version with the `primary-key`, if it exists
          purge-primary-key: never

      - name: Build package
        env:
          # CircleCI build environment looks like it has a zillion and a half cores.
          # Don't let Nix autodetect this high core count because it blows up memory
          # usage and fails the test run.  Pick a number of cores that suits the build
          # environment we're paying for (the free one!).
          DEPENDENCY_CORES: 3
        run: |
          nix build \
            --verbose \
            --print-build-logs \
            --cores "$DEPENDENCY_CORES" \
            --override-input nixpkgs "$NIXPKGS" \
            .#python${{ matrix.python-version }}-tahoe-lafs

      - name: Unit test
        env:
          # Once dependencies are built, we can allow some more concurrency for our own
          # test suite.
          UNITTEST_CORES: 8
        run: |
          nix run \
            --override-input nixpkgs "$NIXPKGS" \
            .#python${{ matrix.python-version }}-unittest -- \
            --jobs $UNITTEST_CORES \
            allmydata