Enable algolia search and indexing

.github/workflows/rebuild-search-index.yml

@@ -0,0 +1,27 @@
+name: Rebuild Search Index
+on:
+  workflow_dispatch:
+permissions: read-all
+jobs:
+  build:
+    if: github.repository_owner == 'spring-projects'
+    runs-on: ubuntu-latest
+    env:
+      CONFIG_FILE: .github/actions/docsearch-config.json
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+      with:
+        fetch-depth: 5
+    - name: Configure Indexer
+      run: |
+        curl -sL -o $CONFIG_FILE $(node -p "require('fs').readFileSync('antora-playbook.yml', 'utf8').match(/^  url: (.*)/m)[1]")/docsearch-config.json
+        INDEX_NAME=$(node -p "JSON.parse(require('fs').readFileSync('$CONFIG_FILE')).index_name")
+        echo "INDEX_NAME_TMP=${INDEX_NAME}-${GITHUB_RUN_ID}" >> $GITHUB_ENV
+    - name: Run Indexer
+      uses: darrenjennings/algolia-docsearch-action@master
+      with:
+        algolia_application_id: ${{ secrets.ALGOLIA_APPLICATION_ID }}
+        algolia_api_key: ${{ secrets.ALGOLIA_WRITE_KEY }}
+        file: ${{ env.CONFIG_FILE }}
+