NVSentinel/.github/workflows/fern-docs-preview-comment.yml at 249915245e2c7785b3bc923c3c3e583093780dd3 · NVIDIA/NVSentinel · GitHub

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# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0

# Workflow 2 of 2 for Fern doc previews.
#
# Triggered by workflow_run after "Preview Fern Docs: Build" completes.
# Downloads the fern/ artifact, generates a preview with DOCS_FERN_TOKEN,
# and posts a stable comment on the PR. This workflow never checks out the
# PR branch directly, keeping secrets isolated from untrusted code.
#
# Required configuration:
# - Organization secret: DOCS_FERN_TOKEN (from `fern token` for the nvidia Fern org)

name: "Preview Fern Docs: Comment"

on:
  workflow_run:
    workflows: ["Preview Fern Docs: Build"]
    types: [completed]

permissions:
  pull-requests: write
  actions: read

jobs:
  preview:
    runs-on: linux-amd64-cpu32
    if: ${{ github.event.workflow_run.conclusion == 'success' }}
    steps:
      - name: Download fern sources and metadata
        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c  # v8.0.1
        with:
          name: fern-preview
          run-id: ${{ github.event.workflow_run.id }}
          github-token: ${{ secrets.GITHUB_TOKEN }}

      - name: Read PR metadata
        id: metadata
        run: |
          echo "pr_number=$(cat preview-metadata/pr_number)" >> "$GITHUB_OUTPUT"
          echo "head_ref=$(cat preview-metadata/head_ref)" >> "$GITHUB_OUTPUT"

      - name: Setup Node.js
        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020  # v7.0.0
        with:
          node-version: '20'

      - name: Install Fern CLI
        run: npm install -g fern-api@$(jq -r .version fern/fern.config.json)

      - name: Generate preview URL
        id: generate-docs
        env:
          FERN_TOKEN: ${{ secrets.DOCS_FERN_TOKEN }}
          HEAD_REF: ${{ steps.metadata.outputs.head_ref }}
        working-directory: ./fern
        run: |
          set -o pipefail
          fern generate --docs --preview --id "$HEAD_REF" 2>&1 | tee /tmp/fern-output.log
          URL=$(grep -oP 'Published docs to \K.*(?= \()' /tmp/fern-output.log || true)
          if [ -z "$URL" ]; then
            echo "::error::Failed to generate preview URL. See fern output above."
            exit 1
          fi
          echo "preview_url=$URL" >> "$GITHUB_OUTPUT"

      - name: Post or update PR comment
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR_NUMBER: ${{ steps.metadata.outputs.pr_number }}
          PREVIEW_URL: ${{ steps.generate-docs.outputs.preview_url }}
        run: |
          MARKER="<!-- fern-preview-docs -->"
          BODY=":herb: **Fern Docs Preview:** <${PREVIEW_URL}>

          ${MARKER}"

          COMMENT_ID=$(gh api "repos/${{ github.repository }}/issues/${PR_NUMBER}/comments" \
            --jq ".[] | select(.body | contains(\"${MARKER}\")) | .id" | head -1)

          if [ -n "$COMMENT_ID" ]; then
            gh api "repos/${{ github.repository }}/issues/comments/${COMMENT_ID}" \
              -X PATCH -f body="$BODY"
          else
            gh api "repos/${{ github.repository }}/issues/${PR_NUMBER}/comments" \
              -f body="$BODY"
          fi