[BugFix] Fix ipv4 address parsing regression (#3645)

vllm/utils.py

@@ -205,7 +205,9 @@ def get_ip() -> str:
 
 
 def get_distributed_init_method(ip: str, port: int) -> str:
-    return f"tcp://[{ip}]:{port}"
+    # Brackets are not permitted in ipv4 addresses,
+    # see https://github.com/python/cpython/issues/103848
+    return f"tcp://[{ip}]:{port}" if ":" in ip else f"tcp://{ip}:{port}"
 
 
 def get_open_port() -> int: