ci.yaml

name: CI

# Controls when the action will run.
on:
  # Triggers the workflow on push or pull request events but only for the main branch
  push:
    branches: [main, es6]
  pull_request:
    branches: [main, es6]

  # Allows you to run this workflow manually from the Actions tab
  workflow_dispatch:

concurrency:
    # Cancel previous actions from the same PR: https://stackoverflow.com/a/72408109
    group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
    cancel-in-progress: true

jobs:
  # matrix-prep-* steps generate JSON used to create a dynamic actions matrix.
  # Insanely complex for how simple this requirement is inspired from
  # https://stackoverflow.com/questions/65384420/how-to-make-a-github-action-matrix-element-conditional

  matrix-prep-bazelversion:
    # Prepares the 'bazelversion' axis of the test matrix
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - id: bazel_from_bazelversion
        run: echo "bazelversion=$(head -n 1 .bazelversion)" >> $GITHUB_OUTPUT
      # bazel 5 testing disabled for now due to
      # https://github.com/aspect-build/bazel-lib/issues/392
      # - id: bazel_5
      #   run: echo "bazelversion=5.3.2" >> $GITHUB_OUTPUT
    outputs:
      # Will look like ["<version from .bazelversion>"]
      bazelversions: ${{ toJSON(steps.*.outputs.bazelversion) }}

  bazel-build:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    needs:
      - matrix-prep-bazelversion

    # Run bazel test in each workspace with each version of Bazel supported
    strategy:
      fail-fast: false
      matrix:
        bazelversion: ${{ fromJSON(needs.matrix-prep-bazelversion.outputs.bazelversions) }}
        folder:
          - "."

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - uses: actions/checkout@v3

      # Cache build and external artifacts so that the next ci build is incremental.
      # Because github action caches cannot be updated after a build, we need to
      # store the contents of each build in a unique cache key, then fall back to loading
      # it on the next ci run. We use hashFiles(...) in the key and restore-keys- with
      # the prefix to load the most recent cache for the branch on a cache miss. You
      # should customize the contents of hashFiles to capture any bazel input sources,
      # although this doesn't need to be perfect. If none of the input sources change
      # then a cache hit will load an existing cache and bazel won't have to do any work.
      # In the case of a cache miss, you want the fallback cache to contain most of the
      # previously built artifacts to minimize build time. The more precise you are with
      # hashFiles sources the less work bazel will have to do.
      - name: Mount bazel caches
        uses: actions/cache@v3
        with:
          path: |
            ~/.cache/bazel
            ~/.cache/bazel-repo
          key: bazel-cache-${{ hashFiles('**/BUILD.bazel', '**/*.bzl', 'WORKSPACE') }}
          restore-keys: bazel-cache-

      - name: Configure Bazel version
        working-directory: ${{ matrix.folder }}
        run: echo "${{ matrix.bazelversion }}" > .bazelversion

      - name: bazel build //generator/...
        env:
          # Bazelisk will download bazel to here, ensure it is cached between runs.
          XDG_CACHE_HOME: ~/.cache/bazel-repo
        working-directory: ${{ matrix.folder }}
        run: bazel --bazelrc=$GITHUB_WORKSPACE/.github/workflows/ci.bazelrc --bazelrc=.github/workflows/ci.bazelrc build //generator/...