ci.yaml

name: Nix CI
"on":
  push: {}
  pull_request: {}
  release:
    types: [edited]
  schedule:
    - cron: 0 0 * * *
  workflow_dispatch: {}

jobs:
  # Check if the action code changed
  check-action-code-changes:
    name: Check if action code changed
    runs-on: ubuntu-latest
    outputs:
      any_changed: ${{ steps.any_changed.outputs.any_changed }}
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 2
      
      - uses: tj-actions/changed-files@v38
        id: any_changed
        with:
          files: |
            src/**
            package.*

  # Build the action if there are changes
  # Commit and push the built code
  build:
    name: Build the action
    runs-on: ubuntu-20.04
    permissions:
      contents: write
      actions: write
    needs: check-action-code-changes
    if: needs.check-action-code-changes.outputs.any_changed
    steps:
      - uses: actions/checkout@v3

      # http://man7.org/linux/man-pages/man1/date.1.html
      - name: Get Date
        id: get-date
        run: |
          echo "date=$(/bin/date -u "+date-%Y-%m-%d-time-%H-%M-%S")" >> $GITHUB_OUTPUT
        shell: bash

      - uses: actions/cache@v3
        with:
          path: |
            ~/.npm
          key: ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json', 'package.json') }}-${{ steps.get-date.outputs.date }}
          restore-keys: |
            ${{ runner.os }}-npm-${{ hashFiles('**/package-lock.json', 'package.json') }}-

      - name: Install packages & Build the action
        run: npm ci

      - name: Commit & Push changes
        if: github.event_name == 'push'
        run: |
          git config --global user.name github-actions
          git config --global user.email github-actions@github.com
          git pull --rebase --autostash
          git add dist
          git commit -m "action: build the action" || echo ""
          git push

  # If ci.yaml changes, need to save a new cache with an updated key
  # For the sake of testing, we assume that ci.yaml changes on every commit
  check-cache-changes:
    name: Check cache changes
    needs: build
    runs-on: ubuntu-20.04
    if: always()
    outputs:
      # assume files-changed so that the 'similar-caches' jobs run always
      files-changed: true
      
      # the following line is more fair
      # files-changed: ${{ steps.files-changed.outputs.any_changed }}
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 2
      - uses: tj-actions/changed-files@v38
        id: files-changed
        with:
          files: |
            .github/workflows/ci.yaml
  
  # Make individual caches with an `id` infix (`id` caches)
  # Restore `id` or `common` caches
  # Usually, there should be no `id` caches as they're purged by `merge-similar-caches`
  make-similar-caches:
    name: Make similar caches
    needs: check-cache-changes
    strategy:
      matrix:
        os:
          - macos-11
          - macos-12
          - ubuntu-20.04
          - ubuntu-22.04
        id:
          - 1
          - 2
    runs-on: ${{ matrix.os }}
    if: always() && needs.check-cache-changes.outputs.files-changed
    steps:
      - name: Checkout this repo
        uses: actions/checkout@v3

      - name: Rebase
        run: git pull --rebase
      
      - uses: nixbuild/nix-quick-install-action@v25
        with:
          nix_conf: |
            substituters = https://cache.nixos.org/ https://nix-community.cachix.org
            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs=
            keep-outputs = true
      - name: Restore and cache Nix store - ${{ matrix.id }}
        uses: ./.
        with:
          # save a new cache every time ci file changes
          key: similar-cache-${{ matrix.os }}-id-${{ matrix.id }}-${{ hashFiles('.github/workflows/ci.yaml') }}
          restore-keys: |
            similar-cache-${{ matrix.os }}-common-
          restore-key-hit: true
  
  # Merge similar individual `id` caches
  # Purge individual caches and old `common` caches
  # Save new `common` caches
  merge-similar-caches:
    name: Merge similar caches
    needs: [check-cache-changes, make-similar-caches]
    permissions:
      actions: write
    strategy:
      matrix:
        os:
          - macos-11
          - macos-12
          - ubuntu-20.04
          - ubuntu-22.04
    runs-on: ${{ matrix.os }}
    if: always() && needs.check-cache-changes.outputs.files-changed
    steps:
      - name: Checkout this repo
        uses: actions/checkout@v3

      - name: Rebase
        run: git pull --rebase
      
      - uses: nixbuild/nix-quick-install-action@v25
        with:
          nix_conf: |
            substituters = https://cache.nixos.org/ https://nix-community.cachix.org
            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs=
            keep-outputs = true
              
      - name: Save Nix store
        uses: ./.
        with:
          key: similar-cache-${{ matrix.os }}-common-${{ hashFiles('.github/workflows/ci.yaml') }}
          extra-restore-keys: |
            similar-cache-${{ matrix.os }}-id-

          purge: true
          purge-keys: |
            similar-cache-${{ matrix.os }}-id-
            similar-cache-${{ matrix.os }}-common-
          purge-created-max-age: 0

  compare-run-times:
    name: Job with caching
    needs: merge-similar-caches
    permissions:
      actions: write
    strategy:
      matrix:
        do-cache:
          - true
          - false
        os:
          - macos-11
          - macos-12
          - ubuntu-20.04
          - ubuntu-22.04
    runs-on: ${{ matrix.os }}
    if: always()
    steps:
      - name: Checkout this repo
        uses: actions/checkout@v3
      
      - name: Rebase
        run: git pull --rebase

      - uses: nixbuild/nix-quick-install-action@v25
        with:
          nix_conf: |
            substituters = https://cache.nixos.org/ https://nix-community.cachix.org
            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs=
            keep-outputs = true

      # -------- THIS ACTION --------
      - name: Restore and cache Nix store
        if: ${{ matrix.do-cache }}
        uses: ./.
        with:
          # save a new cache every time ci file changes
          key: cache-${{ matrix.os }}-${{ hashFiles('.github/workflows/ci.yaml') }}
          restore-keys: |
            cache-${{ matrix.os }}-
          
          gc-linux: true
          gc-max-store-size-linux: 8000000000
          gc-macos: true
          gc-max-store-size-macos: 8000000000
          
          purge: true
          purge-keys: cache-${{ matrix.os }}-
          purge-created: true
          purge-created-max-age: 172800
          
      # -------- THIS ACTION --------
      
      # Uncomment to debug this job
      # - name: Setup tmate session
      #   uses: mxschmitt/action-tmate@v3

      - name: Show profile
        run: nix profile list

      - name: Lock nixpkgs
        run: |
          nix registry add nixpkgs github:NixOS/nixpkgs/5daaa32204e9c46b05cd709218b7ba733d07e80c
          nix profile install $(nix flake archive nixpkgs --json | jq -r '.path')

      - name: Show profile
        run: nix profile list

      - name: Run commands
        run: |
          nix run nixpkgs#hello
          nix profile install nixpkgs#hello
          
          nix profile install nixpkgs#cachix
          
          nix profile install nixpkgs#nixpkgs-fmt
          nix profile install nixpkgs#alejandra
          
          nix profile install nixpkgs#nixd
          
          nix profile install nixpkgs#ghc
          nix profile install nixpkgs#haskell-language-server
          
          nix profile install nixpkgs#purescript
          
          nix profile install nixpkgs#nodejs_18

      - name: Show profile
        run: nix profile list