143 lines
4.6 KiB
Python
143 lines
4.6 KiB
Python
import logging
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from abc import abstractmethod
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from json import loads, dumps
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from subprocess import run, PIPE, Popen
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from functools import partial
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from os import getpgid, killpg
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from os.path import join
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from signal import SIGTERM
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from secrets import token_urlsafe
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from threading import Thread
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from contextlib import suppress
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from pipe_io_server import PipeIOServer, terminate_process_on_failure
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LOG = logging.getLogger(__name__)
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DEFAULT_PERMISSIONS = 0o600
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class PipeIOHandlerBase:
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keys = ['']
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def __init__(self, in_pipe_path, out_pipe_path, permissions=DEFAULT_PERMISSIONS):
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self.connector = None
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self.pipe_io = CallbackPipeIOServer(
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in_pipe_path,
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out_pipe_path,
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self.handle_pipe_event,
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permissions
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)
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self.pipe_io.start()
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@abstractmethod
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def handle_pipe_event(self, message_bytes):
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raise NotImplementedError()
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def cleanup(self):
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self.pipe_io.stop()
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class CallbackPipeIOServer(PipeIOServer):
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def __init__(self, in_pipe_path, out_pipe_path, callback, permissions):
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super().__init__(in_pipe_path, out_pipe_path, permissions)
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self.callback = callback
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def handle_message(self, message):
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try:
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self.callback(message)
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except: # pylint: disable=bare-except
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LOG.exception('Failed to handle message %s from pipe %s!', message, self.in_pipe)
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class PipeIOHandler(PipeIOHandlerBase):
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def handle_event(self, message, _):
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json_bytes = dumps(message).encode()
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self.pipe_io.send_message(json_bytes)
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def handle_pipe_event(self, message_bytes):
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json = loads(message_bytes)
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self.connector.send_message(json)
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class TransformerPipeIOHandler(PipeIOHandlerBase):
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# pylint: disable=too-many-arguments
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def __init__(
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self, in_pipe_path, out_pipe_path,
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transform_in_cmd, transform_out_cmd,
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permissions=DEFAULT_PERMISSIONS
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):
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self._transform_in = partial(self._transform_message, transform_in_cmd)
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self._transform_out = partial(self._transform_message, transform_out_cmd)
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super().__init__(in_pipe_path, out_pipe_path, permissions)
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@staticmethod
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def _transform_message(transform_cmd, message):
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proc = run(
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transform_cmd,
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input=message,
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stdout=PIPE,
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stderr=PIPE,
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shell=True
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)
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if proc.returncode == 0:
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return proc.stdout
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raise ValueError(f'Transforming message {message} failed!')
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def handle_event(self, message, _):
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json_bytes = dumps(message).encode()
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transformed_bytes = self._transform_out(json_bytes)
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if transformed_bytes:
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self.pipe_io.send_message(transformed_bytes)
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def handle_pipe_event(self, message_bytes):
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transformed_bytes = self._transform_in(message_bytes)
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if transformed_bytes:
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json_message = loads(transformed_bytes)
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self.connector.send_message(json_message)
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class CommandHandler(PipeIOHandler):
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def __init__(self, command, permissions=DEFAULT_PERMISSIONS):
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super().__init__(
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self._generate_tempfilename(),
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self._generate_tempfilename(),
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permissions
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)
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self._proc_stdin = open(self.pipe_io.out_pipe, 'rb')
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self._proc_stdout = open(self.pipe_io.in_pipe, 'wb')
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self._proc = Popen(
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command, shell=True, executable='/bin/bash',
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stdin=self._proc_stdin, stdout=self._proc_stdout, stderr=PIPE,
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start_new_session=True
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)
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self._monitor_proc_thread = self._start_monitor_proc()
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def _generate_tempfilename(self):
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# pylint: disable=no-self-use
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random_filename = partial(token_urlsafe, 10)
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return join('/tmp', f'{type(self).__name__}.{random_filename()}')
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def _start_monitor_proc(self):
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thread = Thread(target=self._monitor_proc, daemon=True)
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thread.start()
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return thread
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@terminate_process_on_failure
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def _monitor_proc(self):
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return_code = self._proc.wait()
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if return_code == -int(SIGTERM):
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# supervisord asked the program to terminate, this is fine
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return
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if return_code != 0:
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_, stderr = self._proc.communicate()
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raise RuntimeError(f'Subprocess failed ({return_code})! Stderr:\n{stderr.decode()}')
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def cleanup(self):
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with suppress(ProcessLookupError):
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process_group_id = getpgid(self._proc.pid)
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killpg(process_group_id, SIGTERM)
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self._proc_stdin.close()
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self._proc_stdout.close()
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super().cleanup()
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