ci.yaml

name: Nix CI
"on":
  push:
    # don't run on tags, run on commits
    # https://github.com/orgs/community/discussions/25615
    tags-ignore: 
      - '**'
    branches:
      - '**'
  pull_request: {}
  release:
    types: [edited]
  schedule:
    - cron: 0 0 * * *
  workflow_dispatch: {}

env:
  # https://stackoverflow.com/a/71158878
  git_pull: git pull --rebase origin ${{ github.head_ref || github.ref_name }}

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@v4
  #       with:
  #         fetch-depth: 2
      
  #     - uses: tj-actions/changed-files@v42
  #       id: any_changed
  #       with:
  #         files: |
  #           src/**
  #           package.json
  #           package-lock.json
  #           flake.lock
  #           flake.nix

  # Build the action if there are changes
  # Commit and push the built code
  build:
    name: Build the action
    runs-on: macos-latest
    permissions:
      contents: write
      actions: write
    # needs: check-action-code-changes
    # if: needs.check-action-code-changes.outputs.any_changed
    steps:
      - uses: actions/checkout@v4
      
      - uses: nixbuild/nix-quick-install-action@v26

      - name: Restore and save Nix store
        uses: ./.
        with:
          primary-key: build-${{ runner.os }}-${{ hashFiles('**/package-lock.json', 'package.json', 'flake.nix', 'flake.lock') }}
          paths: |
            ~/.npm
          # do purge caches
          purge: true
          # purge all versions of the cache
          purge-prefixes: build-${{ runner.os }}-
          # 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
          
      # Uncomment to debug this job
      - name: Setup tmate session
        uses: mxschmitt/action-tmate@v3

      - name: Configure github-actions bot
        run: |
          git config --global user.name github-actions
          git config --global user.email github-actions@github.com
      
      - name: Rebase
        run: ${{ env.git_pull }}
      
      - name: Install packages & Build the action
        run: nix run .#install
        
      - name: Update docs
        run: nix run .#write
          
      - name: Commit & push changes
        run: |
          git add dist
          git commit -m "action: build the action" || echo ""
          git add .
          git commit -m "action: update docs" || 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@v4
        with:
          fetch-depth: 2

      - uses: tj-actions/changed-files@v42
        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
    permissions:
      actions: write
    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@v4

      - name: Rebase
        run: ${{ env.git_pull }}
      
      - uses: nixbuild/nix-quick-install-action@v26

      - name: Restore and save Nix store - ${{ matrix.id }}
        uses: ./.
        with:
          # save a new cache every time `ci.yaml` changes
          primary-key: similar-cache-${{ matrix.os }}-individual-${{ matrix.id }}-${{ hashFiles('.github/workflows/ci.yaml') }}
          # otherwise, restore a common cache if and only if it matches the current `ci.yaml`
          restore-prefixes-first-match: similar-cache-${{ matrix.os }}-common-${{ hashFiles('.github/workflows/ci.yaml') }}
          # do purge caches
          purge: true
          # purge all versions of the cache
          purge-prefixes: similar-cache-${{ matrix.os }}-individual-${{ matrix.id }}-
          # 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

  # 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@v4

      - name: Rebase
        run: ${{ env.git_pull }}
      
      - uses: nixbuild/nix-quick-install-action@v26
              
      - name: Restore and save Nix store
        uses: ./.
        with:
          primary-key: similar-cache-${{ matrix.os }}-common-${{ hashFiles('.github/workflows/ci.yaml') }}
          # when there's a common cache hit, don't restore individual caches
          skip-restore-on-hit-primary-key: true
          # otherwise, restore individual caches, but not their old versions
          restore-prefixes-all-matches: |
            similar-cache-${{ matrix.os }}-individual-1-${{ hashFiles('.github/workflows/ci.yaml') }}
            similar-cache-${{ matrix.os }}-individual-2-${{ hashFiles('.github/workflows/ci.yaml') }}
          # do purge caches
          purge: true
          # purge all versions of the cache
          purge-prefixes: similar-cache-${{ matrix.os }}-common-
          # 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

  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@v4
      
      - name: Rebase
        run: ${{ env.git_pull }}

      - uses: nixbuild/nix-quick-install-action@v26

      - name: Restore and save Nix store
        if: ${{ matrix.do-cache }}
        uses: ./.
        with:
          # save a new cache every time ci file changes
          primary-key: cache-${{ matrix.os }}-${{ hashFiles('.github/workflows/ci.yaml') }}
          restore-prefixes-first-match: cache-${{ matrix.os }}-
          # do purge caches
          purge: true
          # purge all versions of the cache
          purge-prefixes: cache-${{ matrix.os }}-
          # 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
          # and collect garbage in the Nix store until it reaches this size in bytes
          gc-max-store-size: 8000000000
      
      # Uncomment to debug this job
      # - name: Setup tmate session
      #   uses: mxschmitt/action-tmate@v3

      - name: Show profile
        run: nix profile list

      - name: Lock and install nixpkgs
        run: |
          nix registry add nixpkgs github:NixOS/nixpkgs/5daaa32204e9c46b05cd709218b7ba733d07e80c
          nix registry list

          nix profile install $(nix flake archive nixpkgs --json | jq -r '.path')

      - name: Show profile
        run: nix profile list

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

      - name: Install nixpkgs#nodejs
        run: |
          nix profile install nixpkgs#nodejs

      - name: Show profile
        run: nix profile list