[Misc] Remove deprecated VLLM_ALL2ALL_BACKEND environment variable (#33535)

Signed-off-by: carlory <baofa.fan@daocloud.io>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

.buildkite/scripts/scheduled_integration_test/deepseek_v2_lite_ep_eplb.sh

@@ -43,7 +43,6 @@ trap cleanup EXIT
 
 for BACK in "${BACKENDS[@]}"; do
   VLLM_DEEP_GEMM_WARMUP=skip \
-  VLLM_ALL2ALL_BACKEND=$BACK \
   vllm serve "$MODEL" \
     --enforce-eager \
     --tensor-parallel-size 2 \
@@ -52,6 +51,7 @@ for BACK in "${BACKENDS[@]}"; do
     --enable-eplb \
     --trust-remote-code \
     --max-model-len 2048 \
+    --all2all-backend $BACK \
     --port $PORT &
   SERVER_PID=$!
   wait_for_server $PORT

tests/kernels/moe/modular_kernel_tools/common.py

@@ -150,10 +150,7 @@ class Config:
             "VLLM_USE_DEEP_GEMM": str(int(self.needs_deep_gemm())),
         }
 
-        backend = self.all2all_backend()
-        vllm_config.parallel_config.all2all_backend = backend
-        if backend is not None:
-            env_dict.update({"VLLM_ALL2ALL_BACKEND": backend})
+        vllm_config.parallel_config.all2all_backend = self.all2all_backend()
 
         if self.fused_moe_chunk_size is not None:
             env_dict.update(

vllm/config/parallel.py

@@ -549,15 +549,6 @@ class ParallelConfig:
         return hash_factors(factors)
 
     def __post_init__(self) -> None:
-        # Set all2all_backend from env var if not specified, with deprecation warning
-        if envs.is_set("VLLM_ALL2ALL_BACKEND"):
-            logger.warning_once(
-                "VLLM_ALL2ALL_BACKEND environment variable is deprecated and "
-                "will be removed in v0.15.0. Please use the "
-                "--all2all-backend command-line argument instead."
-            )
-            self.all2all_backend = envs.VLLM_ALL2ALL_BACKEND
-
         # Continue with the rest of the initialization
         self.world_size = (
             self.pipeline_parallel_size

vllm/envs.py

@@ -171,15 +171,6 @@ if TYPE_CHECKING:
     VLLM_NIXL_SIDE_CHANNEL_HOST: str = "localhost"
     VLLM_NIXL_SIDE_CHANNEL_PORT: int = 5600
     VLLM_MOONCAKE_BOOTSTRAP_PORT: int = 8998
-    VLLM_ALL2ALL_BACKEND: Literal[
-        "naive",
-        "pplx",
-        "deepep_high_throughput",
-        "deepep_low_latency",
-        "mori",
-        "allgather_reducescatter",
-        "flashinfer_all2allv",
-    ] = "allgather_reducescatter"
     VLLM_MAX_TOKENS_PER_EXPERT_FP4_MOE: int = 163840
     VLLM_TOOL_PARSE_REGEX_TIMEOUT_SECONDS: int = 1
     VLLM_SLEEP_WHEN_IDLE: bool = False
@@ -1292,30 +1283,6 @@ environment_variables: dict[str, Callable[[], Any]] = {
     "VLLM_MOONCAKE_BOOTSTRAP_PORT": lambda: int(
         os.getenv("VLLM_MOONCAKE_BOOTSTRAP_PORT", "8998")
     ),
-    # [DEPRECATED - will be removed in v0.15.0] all2all backend for vllm's
-    # expert parallel communication. Use --all2all-backend CLI argument instead.
-    # Available options:
-    # - "naive": naive all2all implementation using broadcasts
-    # - "allgather_reducescatter": all2all implementation based on allgather and
-    #  reducescatter
-    # - "pplx": use pplx kernels
-    # - "deepep_high_throughput", use deepep high-throughput kernels
-    # - "deepep_low_latency", use deepep low-latency kernels
-    # - "mori", use MoRI kernels
-    # - "flashinfer_all2allv", use flashinfer alltoallv kernels for mnnvl
-    "VLLM_ALL2ALL_BACKEND": env_with_choices(
-        "VLLM_ALL2ALL_BACKEND",
-        None,
-        [
-            "naive",
-            "pplx",
-            "deepep_high_throughput",
-            "deepep_low_latency",
-            "mori",
-            "allgather_reducescatter",
-            "flashinfer_all2allv",
-        ],
-    ),
     # Flashinfer MoE backend for vLLM's fused Mixture-of-Experts support.
     # Both require compute capability 10.0 or above.
     # Available options: