Disable build isolation to bypass CUDA related deps for vllm-tpu (#43038)

Signed-off-by: Ylang Tsou <ylangt@google.com>
Co-authored-by: Ylang Tsou <ylangt@google.com>
Co-authored-by: Michael Goin <mgoin64@gmail.com>

requirements/build/tpu.txt

@@ -0,0 +1,7 @@
+--extra-index-url https://download.pytorch.org/whl/cpu
+cmake>=3.26.1
+ninja
+setuptools>=77.0.3,<81.0.0
+setuptools-scm>=8
+torch==2.11.0+cpu
+wheel

tools/vllm-tpu/build.sh

@@ -79,12 +79,15 @@ trap cleanup EXIT HUP INT QUIT PIPE TERM # Register cleanup function to run on s
 
 echo "Updating pyproject.toml completed. Proceeding with build..."
 
+echo "Install dependencies for no-isolation build"
+pip install -r "$VLLM_DIR/requirements/build/tpu.txt"
+
 echo "Building wheel for TPU..."
 rm -rf dist/
 mkdir -p dist/
 
 # User confirmed to use 'python -m build' directly
-if ! VLLM_TARGET_DEVICE=tpu python -m build; then
+if ! VLLM_TARGET_DEVICE=tpu python -m build --no-isolation; then
     echo "Error: Python build command failed. Check if 'python -m build' works and the 'build' module is installed."
     exit 1
 fi