[1/N] Elastic EP Milestone 2 (#34861)

Signed-off-by: Yongji Wu <wuyongji317@gmail.com>
Signed-off-by: Itay Alroy <ialroy@nvidia.com>
Signed-off-by: Tyler Michael Smith <tlrmchlsmth@gmail.com>
Signed-off-by: Ron Tourgeman <rtourgeman@nvidia.com>
Co-authored-by: Yongji Wu <wuyongji317@gmail.com>
Co-authored-by: Tyler Michael Smith <tlrmchlsmth@gmail.com>
Co-authored-by: Ron Tourgeman <rtourgeman@nvidia.com>

tests/distributed/eplb_utils.py

@@ -7,6 +7,7 @@ import random
 import torch
 import torch.multiprocessing as mp
 
+from vllm.config import VllmConfig, set_current_vllm_config
 from vllm.distributed.parallel_state import (
     init_distributed_environment,
 )
@@ -42,7 +43,11 @@ def set_env_vars_and_device(env: dict[str, str]) -> None:
     local_rank = os.environ["LOCAL_RANK"]
     device = torch.device(f"cuda:{local_rank}")
     torch.cuda.set_device(device)
-    init_distributed_environment()
+
+    # Create a minimal vllm config for init_distributed_environment
+    vllm_config = VllmConfig()
+    with set_current_vllm_config(vllm_config):
+        init_distributed_environment()
 
     # Ensure each worker process has the same random seed
     random.seed(42)