Waiting for a TCP port to start accepting connections (Python >=3.6)

wait_for_tcp_port.py

"""
MIT License

Copyright (c) 2017 Michał Bultrowicz

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

import socket
import time


def wait_for_port(port: int, host: str = 'localhost', timeout: float = 5.0):
    """Wait until a port starts accepting TCP connections.
    Args:
        port: Port number.
        host: Host address on which the port should exist.
        timeout: In seconds. How long to wait before raising errors.
    Raises:
        TimeoutError: The port isn't accepting connection after time specified in `timeout`.
    """
    start_time = time.perf_counter()
    while True:
        try:
            with socket.create_connection((host, port), timeout=timeout):
                break
        except OSError as ex:
            time.sleep(0.01)
            if time.perf_counter() - start_time >= timeout:
                raise TimeoutError('Waited too long for the port {} on host {} to start accepting '
                                   'connections.'.format(port, host)) from ex

Hi which license is this? Maybe MIT? 😊

Hi which license is this? Maybe MIT? blush

Yup, it should be MIT :) Adding...

And I can modernize the code a bit, quickly.

EDIT: done :)

Thank you :)