LocalJupyterServer

def __init__(
    self,
    ip: str = "127.0.0.1",
    port: Optional[int] = None,
    token: str | GenerateToken = GenerateToken(),
    log_file: str = "jupyter_gateway.log",
    log_level: str = "INFO",
    log_max_bytes: int = 1048576,
    log_backup_count: int = 3,
):
    """Runs a Jupyter Kernel Gateway server locally.

    Args:
        ip (str, optional): IP address to bind to. Defaults to "127.0.0.1".
        port (Optional[int], optional): Port to use, if None it automatically selects a port. Defaults to None.
        token (Union[str, GenerateToken], optional): Token to use for Jupyter server. By default will generate a token. Using None will use no token for authentication. Defaults to GenerateToken().
        log_file (str, optional): File for Jupyter Kernel Gateway logs. Defaults to "jupyter_gateway.log".
        log_level (str, optional): Level for Jupyter Kernel Gateway logs. Defaults to "INFO".
        log_max_bytes (int, optional): Max logfile size. Defaults to 1048576.
        log_backup_count (int, optional): Number of backups for rotating log. Defaults to 3.
    """
    # Remove as soon as https://github.com/jupyter-server/kernel_gateway/issues/398 is fixed
    if sys.platform == "win32":
        raise ValueError("LocalJupyterServer is not supported on Windows due to kernelgateway bug.")

    # Check Jupyter gateway server is installed
    try:
        subprocess.run(
            [sys.executable, "-m", "jupyter", "kernelgateway", "--version"],
            check=True,
            capture_output=True,
            text=True,
        )
    except subprocess.CalledProcessError:
        raise ValueError(
            "Jupyter gateway server is not installed. Please install it with `pip install jupyter_kernel_gateway`."
        )

    self.ip: str = ip

    if isinstance(token, LocalJupyterServer.GenerateToken):
        token = secrets.token_hex(32)

    self.token: str = token
    self._subprocess: subprocess.Popen[str]
    logging_config = {
        "handlers": {
            "file": {
                "class": "logging.handlers.RotatingFileHandler",
                "level": log_level,
                "maxBytes": log_max_bytes,
                "backupCount": log_backup_count,
                "filename": log_file,
            }
        },
        "loggers": {"KernelGatewayApp": {"level": log_level, "handlers": ["file", "console"]}},
    }

    # Run Jupyter gateway server with detached subprocess
    args = [
        sys.executable,
        "-m",
        "jupyter",
        "kernelgateway",
        "--KernelGatewayApp.ip",
        ip,
        "--KernelGatewayApp.auth_token",
        token,
        "--JupyterApp.answer_yes",
        "true",
        "--JupyterApp.logging_config",
        json.dumps(logging_config),
        "--JupyterWebsocketPersonality.list_kernels",
        "true",
    ]
    if port is not None:
        args.extend(["--KernelGatewayApp.port", str(port)])
        args.extend(["--KernelGatewayApp.port_retries", "0"])
    self._subprocess = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)

    # Satisfy mypy, we know this is not None because we passed PIPE
    assert self._subprocess.stderr is not None
    # Read stderr until we see "is available at" or the process has exited with an error
    stderr = ""
    while True:
        result = self._subprocess.poll()
        if result is not None:
            stderr += self._subprocess.stderr.read()
            raise ValueError(f"Jupyter gateway server failed to start with exit code: {result}. stderr:\n{stderr}")
        line = self._subprocess.stderr.readline()
        stderr += line

        if "ERROR:" in line:
            error_info = line.split("ERROR:")[1]
            raise ValueError(f"Jupyter gateway server failed to start. {error_info}")

        if "is available at" in line:
            # We need to extract what port it settled on
            # Example output:
            #   Jupyter Kernel Gateway 3.0.0 is available at http://127.0.0.1:8890
            if port is None:
                port = int(line.split(":")[-1])
            self.port: int = port

            break

    # Poll the subprocess to check if it is still running
    result = self._subprocess.poll()
    if result is not None:
        raise ValueError(
            f"Jupyter gateway server failed to start. Please check the logs ({log_file}) for more information."
        )

    atexit.register(self.stop)