name: Build docker images

# Controls when the workflow will run
on:
  # Triggers the workflow on push or pull request events but only for the master branch
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

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

# set token permissions for job so we can push to ghcr.io
permissions:
  contents: read
  packages: write

# build components using a job matrix, so they can run in parallel
jobs:
  build:
    runs-on: ubuntu-20.04
    strategy:
      fail-fast: true  # cancel all in-progress jobs if any matrix job fails
      matrix:
        component:
          - downloader
          - restreamer
          - backfiller
          - thrimshim
          - cutter
          - sheetsync
          - nginx
          - postgres
          - segment_coverage
          - playlist_manager
          - chat_archiver
          - zulip_bots
          - bus_analyzer
    steps:
      - name: Check out repo
        uses: actions/checkout@v2
        with:
          submodules: recursive
          # By default, for PR builds, Actions will check out a merge commit between the actual
          # PR branch and the base branch (normally master). This isn't what we want as it means
          # the actually pushed commit isn't getting built, so it can't then be used without being
          # merged first. This makes testing much more difficult.
          # This option makes it actually check out the PR's commit instead.
          ref: ${{ github.event.pull_request.head.sha }}

      - name: Log into ghcr.io
        uses: docker/login-action@v1
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build ${{ matrix.component }}
        # always push
        # if not a pull request and a push to master, also push "latest" tag
        # try to cache from previous build and then build component using build script
        run: |
          export PUSH=true
          if [ "$GITHUB_EVENT_NAME" != "pull_request" ] && [ "$GITHUB_REF" == "refs/heads/master" ]; then export PUSH=latest; fi
          CACHE_FROM=$(git rev-list HEAD -n1 --parents | cut -d" " -f 2-) ./build ${{ matrix.component }}