matrix-spec/.github/workflows/netlify.yaml

# GHA workflow which publishes previews of spec PRs to netlify.
#
# We keep this in a separate workflow to the main spec build, because it
# requires access to the Netlify secret. By having it run on `workflow_run`, we
# will only use the workflow definition file on the default branch, so we can
# ensure that the secret can't be exfiltrated.
#

name: Upload Preview Build to Netlify
on:
  workflow_run:
    workflows: [Spec]
    types: [completed]

jobs:
  build:
    runs-on: ubuntu-latest
    if: github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.event == 'pull_request'
    steps:
      - name: "dump context data"
        run: |
          jq . < $GITHUB_EVENT_PATH
                    
      - name: "🔍 Read PR number"
        id: readctx
        # we need to find the PR number that corresponds to the branch, which we do by
        # searching the GH API
        run: |
          head_branch='${{github.event.workflow_run.head_repository.owner.login}}:${{github.event.workflow_run.head_branch}}'
          echo "head branch: $head_branch"
          pulls_uri="https://api.github.com/repos/${{ github.repository }}/pulls?head=$(jq -Rr '@uri' <<<$head_branch)"
          pr_number=$(curl -H 'Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}' "$pulls_uri" |
               jq -r '.[] | .number')
          echo "PR number: $pr_number"
          echo "::set-output name=prnumber::$pr_number"          
        
      - name: '📥 Download artifact'
        uses: dawidd6/action-download-artifact@268677152d06ba59fcec7a7f0b5d961b6ccd7e1e # v2.28.0
        with:
          workflow: main.yaml
          run_id: ${{ github.event.workflow_run.id }}
          name: spec-artifact

      - name: "📦 Extract Artifacts"
        run: tar -xzvf spec.tar.gz && rm spec.tar.gz
        
      - name: "📤 Deploy to Netlify"
        id: netlify
        # v2.1.0
        uses: nwtgck/actions-netlify@7a92f00dde8c92a5a9e8385ec2919775f7647352
        with:
          publish-dir: spec
          deploy-message: "Deploy from GitHub Actions"
          enable-pull-request-comment: false
          enable-commit-comment: false
          alias: pr${{ steps.readctx.outputs.prnumber }}
        env:
          NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}
          NETLIFY_SITE_ID: ${{ secrets.NETLIFY_SITE_ID }}
        timeout-minutes: 1

      - name: "📝 Edit PR Description"
        # v1.0.1
        uses: Beakyn/gha-comment-pull-request@2167a7aee24f9e61ce76a23039f322e49a990409
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          pull-request-number: ${{ steps.readctx.outputs.prnumber }}
          description-message: |
                        Preview: ${{ steps.netlify.outputs.deploy-url }}