Configure Git LFS authentication and fetch LFS objects for submodule

Author: bhimrazy

.github/workflows/docs-build.yml

@@ -71,26 +71,34 @@ jobs:
           # only Pytorch has/uses notebooks
           submodules: ${{ matrix.pkg-name == 'pytorch' }}
           lfs: false # Disable LFS during checkout to avoid auth issues
-      - name: Setup LFS and fetch notebooks manually
+      - name: Configure Git LFS authentication
         if: ${{ matrix.pkg-name == 'pytorch' }}
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          cd _notebooks
-
-          # Skip LFS entirely - download files directly from GitHub
-          echo "Bypassing LFS - downloading files directly via GitHub API..."
-
-          # List LFS tracked files and download them directly
-          git lfs ls-files --name-only | while read file; do
-            if [ -f "$file" ]; then
-              echo "Downloading $file..."
-              # Download the actual file content from GitHub raw API
-              curl -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
-                   -L "https://github.com/Lightning-AI/lightning-tutorials/raw/HEAD/$file" \
-                   -o "$file"
-            fi
-          done
-
-          echo "Direct download completed"
+          # Configure Git LFS with proper authentication using recommended approach
+          git config --global credential.helper store
+          echo "https://${{ github.actor }}:${GH_TOKEN}@github.com" > ~/.git-credentials
+
+          # Set LFS configuration to use GitHub token
+          git config --global lfs."https://github.com/".access basic
+          git config --global lfs."https://github.com/".locksverify false
+
+      - name: Fetch LFS objects for submodule
+        if: ${{ matrix.pkg-name == 'pytorch' }}
+        working-directory: _notebooks
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          # Initialize LFS in submodule context
+          git lfs install --local
+
+          # Set the correct LFS endpoint with authentication (using the actual repo name)
+          git config lfs.url "https://${{ github.actor }}:${GH_TOKEN}@github.com/Lightning-AI/tutorials.git/info/lfs"
+
+          # Fetch and checkout LFS objects
+          git lfs fetch --all
+          git lfs checkout
       - uses: actions/setup-python@v6
         with:
           python-version: "3.10"