#!/usr/bin/env python3

import asyncio
from subprocess import run, check_call

import aiohttp

# Update these to be valid IPs
ips = ["a.b.c.d", "a.b.c.e"] 
host = "my-static-hostname.example.com"

etc_hosts = "\n".join([f"{ip} {host}" for ip in ips])

url = f"https://{host}"
timeout = 3


async def main():
    # 1. Set up static IP
    with open("/etc/hosts") as f:
        content = f.read()

    if etc_hosts not in content:
        with open("/etc/hosts", "a") as f:
            print(etc_hosts, file=f)

    # 2. Drop all traffic to first IP
    ssl_opts = ["-p", "tcp", "-m", "tcp", "--dport", "443"]
    opts = ["OUTPUT", "-d", ips[0], *ssl_opts, "-j", "DROP"]
    run(["iptables", "-D", *opts])  # remove from previous run if present
    check_call(["iptables", "-A", *opts])

    # 3. Try to connect
    async with aiohttp.ClientSession(conn_timeout=timeout) as client:
        async with client.get(url) as r:
            print(r.status)


if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())


### Expected behavior

Whether via `/etc/hosts` or a DNS server response with multiple IPs, aiohttp should try connecting to all IPs in the resolved list, regardless of the reason for connection failure, until it has successfully connected to one IP or failed to connect to them all.

### Logs/tracebacks

```python-traceback
Note: actual IPs and hostnames replaced with placeholders.


(venv) root@39d71fd1e451:/src# python ./docker/static_ip_failover.py
iptables: Bad rule (does a matching rule exist in that chain?).
/src/./docker/static_ip_failover.py:31: DeprecationWarning: conn_timeout is deprecated, use timeout argument instead
  async with aiohttp.ClientSession(conn_timeout=timeout) as client:
Trying to connect to a.b.c.d
Traceback (most recent call last):
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/client.py", line 536, in _request
    conn = await self._connector.connect(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/connector.py", line 540, in connect
    proto = await self._create_connection(req, traces, timeout)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/connector.py", line 901, in _create_connection
    _, proto = await self._create_direct_connection(req, traces, timeout)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/connector.py", line 1176, in _create_direct_connection
    transp, proto = await self._wrap_create_connection(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/connector.py", line 980, in _wrap_create_connection
    return await self._loop.create_connection(*args, **kwargs)  # type: ignore[return-value]  # noqa
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/asyncio/base_events.py", line 1069, in create_connection
    sock = await self._connect_sock(
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/asyncio/base_events.py", line 973, in _connect_sock
    await self.sock_connect(sock, address)
  File "/usr/local/lib/python3.11/asyncio/selector_events.py", line 634, in sock_connect
    return await fut
           ^^^^^^^^^
asyncio.exceptions.CancelledError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/client.py", line 534, in _request
    async with ceil_timeout(real_timeout.connect):
  File "/src/build_output/venv/lib/python3.11/site-packages/async_timeout/__init__.py", line 129, in __aexit__
    self._do_exit(exc_type)
  File "/src/build_output/venv/lib/python3.11/site-packages/async_timeout/__init__.py", line 212, in _do_exit
    raise asyncio.TimeoutError
TimeoutError

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/src/./docker/static_ip_failover.py", line 38, in <module>
    loop.run_until_complete(main())
  File "/usr/local/lib/python3.11/asyncio/base_events.py", line 653, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/src/./docker/static_ip_failover.py", line 32, in main
    async with client.get(url) as r:
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/client.py", line 1141, in __aenter__
    self._resp = await self._coro
                 ^^^^^^^^^^^^^^^^
  File "/src/build_output/venv/lib/python3.11/site-packages/aiohttp/client.py", line 540, in _request
    raise ServerTimeoutError(
aiohttp.client_exceptions.ServerTimeoutError: Connection timeout to host https://my-static-hostname.example.com