fork-preview-deploy.yml

name: Fork Preview Deploy

on:
  workflow_run:
    workflows:
      - Fork Preview Build
    types:
      - completed

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

concurrency:
  group: fork-preview-deploy-${{ github.event.workflow_run.id }}
  cancel-in-progress: false

jobs:
  deploy:
    if: >
      github.event.workflow_run.conclusion == 'success' &&
      github.event.workflow_run.event == 'pull_request' &&
      github.event.workflow_run.head_repository.full_name != github.repository
    runs-on: ubuntu-latest
    env:
      PREVIEW_PROJECT: ${{ vars.CLOUDFLARE_PREVIEW_PAGES_PROJECT }}

    steps:
      - name: Validate preview project configuration
        run: |
          set -euo pipefail
          if [ -z "${PREVIEW_PROJECT}" ]; then
            echo "Repository variable CLOUDFLARE_PREVIEW_PAGES_PROJECT is required." >&2
            exit 1
          fi

      - name: Download preview artifact
        uses: actions/download-artifact@v8
        with:
          name: pr-preview-site
          path: preview-artifact
          run-id: ${{ github.event.workflow_run.id }}
          github-token: ${{ secrets.GITHUB_TOKEN }}

      - name: Read preview metadata
        id: meta
        run: |
          set -euo pipefail

          metadata_file="preview-artifact/.preview-artifact/metadata.json"
          pr_number="$(jq -r '.pr_number' "${metadata_file}")"
          head_sha="$(jq -r '.head_sha' "${metadata_file}")"
          head_ref="$(jq -r '.head_ref' "${metadata_file}")"
          preview_branch="pr-${pr_number}"

          {
            echo "pr_number=${pr_number}"
            echo "head_sha=${head_sha}"
            echo "head_ref=${head_ref}"
            echo "preview_branch=${preview_branch}"
          } >> "${GITHUB_OUTPUT}"

      - name: Setup Node.js
        uses: actions/setup-node@v6
        with:
          node-version: 24.15.0

      - name: Deploy preview to Cloudflare Pages
        id: deploy
        run: |
          set -euo pipefail

          deploy_log="$(mktemp)"

          npx wrangler@4 pages deploy preview-artifact/build \
            --project-name "${PREVIEW_PROJECT}" \
            --branch "${{ steps.meta.outputs.preview_branch }}" \
            --commit-hash "${{ steps.meta.outputs.head_sha }}" \
            --commit-message "PR #${{ steps.meta.outputs.pr_number }} preview deployment" \
            | tee "${deploy_log}"

          preview_url="$(
            sed -n 's/^.*Deployment alias URL: \(https:\/\/[^[:space:]]*\).*$/\1/p' "${deploy_log}" | tail -n 1
          )"

          if [ -z "${preview_url}" ]; then
            echo "Unable to determine Cloudflare preview alias URL from Wrangler output." >&2
            exit 1
          fi

          echo "preview_url=${preview_url}" >> "${GITHUB_OUTPUT}"
        env:
          CLOUDFLARE_API_TOKEN: ${{ secrets.CLOUDFLARE_DEPLOY_TOKEN }}
          CLOUDFLARE_ACCOUNT_ID: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}

      - name: Upsert preview comment
        uses: actions/github-script@v9
        env:
          PREVIEW_URL: ${{ steps.deploy.outputs.preview_url }}
          HEAD_REF: ${{ steps.meta.outputs.head_ref }}
        with:
          script: |
            const prNumber = Number("${{ steps.meta.outputs.pr_number }}");
            const body = [
              "## Cloudflare Preview",
              "",
              `Preview URL: ${process.env.PREVIEW_URL}`,
              `Source branch: \`${process.env.HEAD_REF}\``,
              `Run: ${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`,
            ].join("\n");

            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
            });

            const existing = comments.find((comment) =>
              comment.user?.type === "Bot" && comment.body?.startsWith("## Cloudflare Preview")
            );

            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body,
              });
              return;
            }

            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
              body,
            });