Enhance run_cluster.sh for multi-NIC support (vllm-project#28328)

Signed-off-by: Ev Lacey <elacey@nvidia.com>

Author: evberrypi

examples/online_serving/run_cluster.sh

@@ -83,6 +83,29 @@ else
     RAY_START_CMD+=" --address=${HEAD_NODE_ADDRESS}:6379"
 fi
 
+# Parse VLLM_HOST_IP from additional args if present.
+# This is needed for multi-NIC configurations where Ray needs explicit IP bindings.
+VLLM_HOST_IP=""
+for arg in "${ADDITIONAL_ARGS[@]}"; do
+    if [[ $arg == "-e" ]]; then
+        continue
+    fi
+    if [[ $arg == VLLM_HOST_IP=* ]]; then
+        VLLM_HOST_IP="${arg#VLLM_HOST_IP=}"
+        break
+    fi
+done
+
+# Build Ray IP environment variables if VLLM_HOST_IP is set.
+# These variables ensure Ray binds to the correct network interface on multi-NIC systems.
+RAY_IP_VARS=()
+if [ -n "${VLLM_HOST_IP}" ]; then
+    RAY_IP_VARS=(
+        -e "RAY_NODE_IP_ADDRESS=${VLLM_HOST_IP}"
+        -e "RAY_OVERRIDE_NODE_IP_ADDRESS=${VLLM_HOST_IP}"
+    )
+fi
+
 # Launch the container with the assembled parameters.
 # --network host: Allows Ray nodes to communicate directly via host networking
 # --shm-size 10.24g: Increases shared memory
@@ -95,5 +118,6 @@ docker run \
     --shm-size 10.24g \
     --gpus all \
     -v "${PATH_TO_HF_HOME}:/root/.cache/huggingface" \
+    "${RAY_IP_VARS[@]}" \
     "${ADDITIONAL_ARGS[@]}" \
     "${DOCKER_IMAGE}" -c "${RAY_START_CMD}"