[PD] Support get local ip from NIC for PD disaggregation (#7237)

Signed-off-by: Shangming Cai <caishangming@linux.alibaba.com>

python/sglang/srt/disaggregation/mooncake/conn.py

@@ -35,12 +35,7 @@ from sglang.srt.disaggregation.common.utils import (
 from sglang.srt.disaggregation.mooncake.transfer_engine import MooncakeTransferEngine
 from sglang.srt.disaggregation.utils import DisaggregationMode
 from sglang.srt.server_args import ServerArgs
-from sglang.srt.utils import (
-    get_free_port,
-    get_int_env_var,
-    get_ip,
-    get_local_ip_by_remote,
-)
+from sglang.srt.utils import get_free_port, get_int_env_var, get_ip, get_local_ip_auto
 
 logger = logging.getLogger(__name__)
 
@@ -130,8 +125,9 @@ class MooncakeKVManager(BaseKVManager):
         is_mla_backend: Optional[bool] = False,
     ):
         self.kv_args = args
+        self.local_ip = get_local_ip_auto()
         self.engine = MooncakeTransferEngine(
-            hostname=get_local_ip_by_remote(),
+            hostname=self.local_ip,
             gpu_id=self.kv_args.gpu_id,
             ib_device=self.kv_args.ib_device,
         )
@@ -432,7 +428,7 @@ class MooncakeKVManager(BaseKVManager):
 
     def start_prefill_thread(self):
         self.rank_port = get_free_port()
-        self.server_socket.bind(f"tcp://{get_local_ip_by_remote()}:{self.rank_port}")
+        self.server_socket.bind(f"tcp://{self.local_ip}:{self.rank_port}")
 
         def bootstrap_thread():
             """This thread recvs pre-alloc notification from the decode engine"""
@@ -471,7 +467,7 @@ class MooncakeKVManager(BaseKVManager):
 
     def start_decode_thread(self):
         self.rank_port = get_free_port()
-        self.server_socket.bind(f"tcp://{get_local_ip_by_remote()}:{self.rank_port}")
+        self.server_socket.bind(f"tcp://{self.local_ip}:{self.rank_port}")
 
         def decode_thread():
             while True:
@@ -620,7 +616,7 @@ class MooncakeKVManager(BaseKVManager):
             "role": "Prefill",
             "tp_size": self.tp_size,
             "dp_size": self.dp_size,
-            "rank_ip": get_local_ip_by_remote(),
+            "rank_ip": self.local_ip,
             "rank_port": self.rank_port,
             "engine_rank": self.kv_args.engine_rank,
         }
@@ -953,7 +949,7 @@ class MooncakeKVReceiver(BaseKVReceiver):
                 sock.send_multipart(
                     [
                         "None".encode("ascii"),
-                        get_local_ip_by_remote().encode("ascii"),
+                        self.kv_mgr.local_ip.encode("ascii"),
                         str(self.kv_mgr.rank_port).encode("ascii"),
                         self.session_id.encode("ascii"),
                         packed_kv_data_ptrs,
@@ -983,7 +979,7 @@ class MooncakeKVReceiver(BaseKVReceiver):
                 sock.send_multipart(
                     [
                         str(self.bootstrap_room).encode("ascii"),
-                        get_local_ip_by_remote().encode("ascii"),
+                        self.kv_mgr.local_ip.encode("ascii"),
                         str(self.kv_mgr.rank_port).encode("ascii"),
                         self.session_id.encode("ascii"),
                         kv_indices.tobytes() if not is_dummy else b"",

python/sglang/srt/utils.py

@@ -2141,6 +2141,44 @@ def get_free_port():
             return s.getsockname()[1]
 
 
+def get_local_ip_auto() -> str:
+    interface = os.environ.get("SGLANG_LOCAL_IP_NIC", None)
+    return (
+        get_local_ip_by_nic(interface)
+        if interface is not None
+        else get_local_ip_by_remote()
+    )
+
+
+def get_local_ip_by_nic(interface: str) -> str:
+    try:
+        import netifaces
+    except ImportError as e:
+        raise ImportError(
+            "Environment variable SGLANG_LOCAL_IP_NIC requires package netifaces, please install it through 'pip install netifaces'"
+        ) from e
+
+    try:
+        addresses = netifaces.ifaddresses(interface)
+        if netifaces.AF_INET in addresses:
+            for addr_info in addresses[netifaces.AF_INET]:
+                ip = addr_info.get("addr")
+                if ip and ip != "127.0.0.1" and ip != "0.0.0.0":
+                    return ip
+        if netifaces.AF_INET6 in addresses:
+            for addr_info in addresses[netifaces.AF_INET6]:
+                ip = addr_info.get("addr")
+                if ip and not ip.startswith("fe80::") and ip != "::1":
+                    return ip.split("%")[0]
+    except (ValueError, OSError) as e:
+        raise ValueError(
+            "Can not get local ip from NIC. Please verify whether SGLANG_LOCAL_IP_NIC is set correctly."
+        )
+
+    # Fallback
+    return get_local_ip_by_remote()
+
+
 def get_local_ip_by_remote() -> str:
     # try ipv4
     s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)