[BugFix] Fix ipv4 address parsing regression

[njhill]

#3641 was a fix for ipv6 but broke ipv4 case.

  File "/workspace/vllm/worker/worker.py", line 100, in init_device
    init_distributed_environment(self.parallel_config, self.rank,
  File "/workspace/vllm/worker/worker.py", line 269, in init_distributed_environment
    torch.distributed.init_process_group(
  File "/opt/vllm/lib/python3.11/site-packages/torch/distributed/c10d_logger.py", line 74, in wrapper
    func_return = func(*args, **kwargs)
                  ^^^^^^^^^^^^^^^^^^^^^
  File "/opt/vllm/lib/python3.11/site-packages/torch/distributed/distributed_c10d.py", line 1138, in init_process_group
    rendezvous_iterator = rendezvous(
                          ^^^^^^^^^^^
  File "/opt/vllm/lib/python3.11/site-packages/torch/distributed/rendezvous.py", line 98, in rendezvous
    return _rendezvous_helper(url, rank, world_size, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/vllm/lib/python3.11/site-packages/torch/distributed/rendezvous.py", line 60, in _rendezvous_helper
    result = urlparse(url)
             ^^^^^^^^^^^^^
  File "/opt/vllm/lib/python3.11/urllib/parse.py", line 395, in urlparse
    splitresult = urlsplit(url, scheme, allow_fragments)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/vllm/lib/python3.11/urllib/parse.py", line 500, in urlsplit
    _check_bracketed_host(bracketed_host)
  File "/opt/vllm/lib/python3.11/urllib/parse.py", line 448, in _check_bracketed_host
    raise ValueError(f"An IPv4 address cannot be in brackets")
ValueError: An IPv4 address cannot be in brackets

[simon-mo]

ahhh we really some tests catching all of these 😮‍💨

[youkaichao]

Is it urllib version related? I can have ipv4 in bracket:

import urllib.parse
urllib.parse.urlparse("tcp://[127.0.0.1]:8080").hostname # 127.0.0.1

I'm using python 3.10 .

[njhill]

Hmm, we are using python 3.11

[njhill]

@youkaichao looks like this was "fixed" recently in cpython python/cpython#103848

[youkaichao]

Let's add some comment there for future clarification then.