[bugfix] fix proxy hen host ip using domain name (#4243)

### What this PR does / why we need it?
fix proxy when host ip using domain name

- vLLM version: v0.11.0
- vLLM main:
2918c1b49c

---------

Signed-off-by: liziyu <liziyu16@huawei.com>

examples/disaggregated_prefill_v1/load_balance_proxy_layerwise_server_example.py

@@ -116,13 +116,13 @@ class ServerState:
     def __init__(self, host, port):
         self.host = host
         self.port = port
-        ip = ipaddress.ip_address(self.host)
-        if isinstance(ip, ipaddress.IPv4Address):
-            self.url = f'http://{host}:{port}/v1'
-        elif isinstance(ip, ipaddress.IPv6Address):
-            self.url = f'http://[{host}]:{port}/v1'
-        else:
-            raise RuntimeError(f"Invild host IP address {ip}")
+        self.url = f'http://{host}:{port}/v1'
+        try:
+            ip = ipaddress.ip_address(self.host)
+            if isinstance(ip, ipaddress.IPv6Address):
+                self.url = f'http://[{host}]:{port}/v1'
+        except Exception:
+            pass
         self.client = httpx.AsyncClient(timeout=None,
                                         base_url=self.url,
                                         limits=httpx.Limits(

examples/disaggregated_prefill_v1/load_balance_proxy_server_example.py

@@ -118,13 +118,13 @@ class ServerState:
     def __init__(self, host, port):
         self.host = host
         self.port = port
-        ip = ipaddress.ip_address(self.host)
-        if isinstance(ip, ipaddress.IPv4Address):
-            self.url = f'http://{host}:{port}/v1'
-        elif isinstance(ip, ipaddress.IPv6Address):
-            self.url = f'http://[{host}]:{port}/v1'
-        else:
-            raise RuntimeError(f"Invild host IP address {ip}")
+        self.url = f'http://{host}:{port}/v1'
+        try:
+            ip = ipaddress.ip_address(self.host)
+            if isinstance(ip, ipaddress.IPv6Address):
+                self.url = f'http://[{host}]:{port}/v1'
+        except Exception:
+            pass
         self.client = httpx.AsyncClient(timeout=None,
                                         base_url=self.url,
                                         limits=httpx.Limits(