preview.yml

name: Preview Documentation

on:
  issue_comment:
    types:
      - created

permissions:
  contents: read
  issues: write
  pull-requests: write

concurrency:
  group: preview-pr-${{ github.event.issue.number }}
  cancel-in-progress: true

jobs:
  preview:
    name: Build and serve preview
    if: >-
      github.event.issue.pull_request &&
      (
        github.event.comment.body == 'preview' ||
        github.event.comment.body == '/preview'
      ) &&
      contains(fromJSON('["OWNER", "MEMBER", "COLLABORATOR"]'), github.event.comment.author_association)
    runs-on: ubuntu-latest
    timeout-minutes: 360

    steps:
      - name: Authorize preview request
        uses: actions/github-script@v7
        with:
          script: |
            const actor = context.payload.comment.user.login;
            const { owner, repo } = context.repo;
            let permission = 'none';

            try {
              const { data } = await github.rest.repos.getCollaboratorPermissionLevel({
                owner,
                repo,
                username: actor,
              });
              permission = data.permission;
            } catch (error) {
              if (error.status !== 404) {
                throw error;
              }
            }

            const allowed = new Set(['admin', 'maintain', 'write']);
            if (!allowed.has(permission)) {
              core.setFailed(
                `Preview builds are limited to repository members with write access. ` +
                `${actor} has ${permission} access.`
              );
            }

      - name: Get pull request
        id: pr
        uses: actions/github-script@v7
        with:
          script: |
            const { owner, repo } = context.repo;
            const pull_number = context.payload.issue.number;
            const { data: pull } = await github.rest.pulls.get({
              owner,
              repo,
              pull_number,
            });

            core.setOutput('head_repo', pull.head.repo.full_name);
            core.setOutput('head_ref', pull.head.ref);
            core.setOutput('head_sha', pull.head.sha);

      - name: React to preview request
        uses: actions/github-script@v7
        continue-on-error: true
        with:
          script: |
            await github.rest.reactions.createForIssueComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              comment_id: context.payload.comment.id,
              content: 'rocket',
            });

      - name: Checkout pull request
        uses: actions/checkout@v4
        with:
          repository: ${{ steps.pr.outputs.head_repo }}
          ref: ${{ steps.pr.outputs.head_sha }}
          persist-credentials: false

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: "20"
          cache: "yarn"

      - name: Install dependencies
        run: yarn install --frozen-lockfile

      - name: Build documentation
        run: yarn build

      - name: Install cloudflared
        run: |
          curl -L https://github.com/cloudflare/cloudflared/releases/latest/download/cloudflared-linux-amd64.deb -o cloudflared.deb
          sudo dpkg -i cloudflared.deb

      - name: Start Docusaurus server
        run: |
          nohup yarn serve --host 0.0.0.0 --port 3000 > docusaurus-preview.log 2>&1 &

      - name: Start preview tunnel
        id: tunnel
        run: |
          nohup cloudflared tunnel --url http://localhost:3000 --no-autoupdate > cloudflared-preview.log 2>&1 &

          for attempt in {1..30}; do
            preview_url="$(grep -o 'https://[^ ]*trycloudflare.com' cloudflared-preview.log | head -n 1 || true)"
            if [ -n "$preview_url" ]; then
              echo "url=$preview_url" >> "$GITHUB_OUTPUT"
              exit 0
            fi

            sleep 2
          done

          echo "Failed to start preview tunnel."
          cat cloudflared-preview.log
          exit 1

      - name: Comment preview URL
        uses: actions/github-script@v7
        env:
          PREVIEW_URL: ${{ steps.tunnel.outputs.url }}
        with:
          script: |
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.payload.issue.number,
              body: [
                `Preview: ${process.env.PREVIEW_URL}`,
                '',
                'This preview will stay live for up to 6 hours. Comment `preview` again to replace it with a fresh build.',
              ].join('\n'),
            });

      - name: Keep preview live for up to six hours
        run: sleep 21600