Waiting for a TCP port ready to accept connections

wait_port_ready.py

"""Thanks to https://gist.github.com/butla/2d9a4c0f35ea47b7452156c96a4e7b12"""

import socket
import time


def wait_port_ready(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 e:
            time.sleep(0.01)
            if time.perf_counter() - start_time >= timeout:
                raise TimeoutError(
                    f'Waited too long for `{host}:{port}` ready to accept connections.'
                ) from e