evaluation_plane_handler.py

from tabpy.tabpy_server.handlers import BaseHandler
import json
import logging
from tabpy.tabpy_server.common.util import format_exception
import requests
from tornado import gen
from datetime import timedelta


class RestrictedTabPy:
    def __init__(self, protocol, port, logger, timeout):
        self.protocol = protocol
        self.port = port
        self.logger = logger
        self.timeout = timeout

    def query(self, name, *args, **kwargs):
        url = f"{self.protocol}://localhost:{self.port}/query/{name}"
        self.logger.log(logging.DEBUG, f"Querying {url}...")
        internal_data = {"data": args or kwargs}
        data = json.dumps(internal_data)
        headers = {"content-type": "application/json"}
        response = requests.post(
            url=url, data=data, headers=headers, timeout=self.timeout, verify=False
        )
        return response.json()


class EvaluationPlaneHandler(BaseHandler):
    """
    EvaluationPlaneHandler is responsible for running arbitrary python scripts.
    """

    def initialize(self, executor, app):
        super(EvaluationPlaneHandler, self).initialize(app)
        self.executor = executor
        self._error_message_timeout = (
            f"User defined script timed out. "
            f"Timeout is set to {self.eval_timeout} s."
        )

    @gen.coroutine
    def post(self):
        if self.should_fail_with_not_authorized():
            self.fail_with_not_authorized()
            return

        self._add_CORS_header()
        try:
            body = json.loads(self.request.body.decode("utf-8"))
            if "script" not in body:
                self.error_out(400, "Script is empty.")
                return

            # Transforming user script into a proper function.
            user_code = body["script"]
            arguments = None
            arguments_str = ""
            if "data" in body:
                arguments = body["data"]

            if arguments is not None:
                if not isinstance(arguments, dict):
                    self.error_out(
                        400, "Script parameters need to be provided as a dictionary."
                    )
                    return
                else:
                    arguments_expected = []
                    for i in range(1, len(arguments.keys()) + 1):
                        arguments_expected.append("_arg" + str(i))
                    if sorted(arguments_expected) == sorted(arguments.keys()):
                        arguments_str = ", " + ", ".join(arguments.keys())
                    else:
                        self.error_out(
                            400,
                            "Variables names should follow "
                            "the format _arg1, _arg2, _argN",
                        )
                        return

            function_to_evaluate = f"def _user_script(tabpy{arguments_str}):\n"
            for u in user_code.splitlines():
                function_to_evaluate += " " + u + "\n"

            self.logger.log(
                logging.INFO, f"function to evaluate={function_to_evaluate}"
            )

            try:
                result = yield self._call_subprocess(function_to_evaluate, arguments)
            except (
                gen.TimeoutError,
                requests.exceptions.ConnectTimeout,
                requests.exceptions.ReadTimeout,
            ):
                self.logger.log(logging.ERROR, self._error_message_timeout)
                self.error_out(408, self._error_message_timeout)
                return

            if result is None:
                self.error_out(400, "Error running script. No return value")
            else:
                self.write(json.dumps(result))
                self.finish()

        except Exception as e:
            err_msg = f"{e.__class__.__name__} : {str(e)}"
            if err_msg != "KeyError : 'response'":
                err_msg = format_exception(e, "POST /evaluate")
                self.error_out(500, "Error processing script", info=err_msg)
            else:
                self.error_out(
                    404,
                    "Error processing script",
                    info="The endpoint you're "
                    "trying to query did not respond. Please make sure the "
                    "endpoint exists and the correct set of arguments are "
                    "provided.",
                )

    @gen.coroutine
    def _call_subprocess(self, function_to_evaluate, arguments):
        restricted_tabpy = RestrictedTabPy(
            self.protocol, self.port, self.logger, self.eval_timeout
        )
        # Exec does not run the function, so it does not block.
        exec(function_to_evaluate, globals())

        if arguments is None:
            future = self.executor.submit(_user_script, restricted_tabpy)
        else:
            future = self.executor.submit(_user_script, restricted_tabpy, **arguments)

        ret = yield gen.with_timeout(timedelta(seconds=self.eval_timeout), future)
        raise gen.Return(ret)