330 lines
11 KiB
Python
330 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2019 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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Log formatters that output terse JSON.
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"""
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import json
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import sys
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import traceback
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from collections import deque
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from ipaddress import IPv4Address, IPv6Address, ip_address
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from math import floor
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from typing import IO, Optional
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import attr
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from zope.interface import implementer
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from twisted.application.internet import ClientService
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from twisted.internet.defer import Deferred
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from twisted.internet.endpoints import (
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HostnameEndpoint,
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TCP4ClientEndpoint,
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TCP6ClientEndpoint,
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)
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from twisted.internet.interfaces import IPushProducer, ITransport
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from twisted.internet.protocol import Factory, Protocol
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from twisted.logger import FileLogObserver, ILogObserver, Logger
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_encoder = json.JSONEncoder(ensure_ascii=False, separators=(",", ":"))
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def flatten_event(event: dict, metadata: dict, include_time: bool = False):
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"""
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Flatten a Twisted logging event to an dictionary capable of being sent
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as a log event to a logging aggregation system.
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The format is vastly simplified and is not designed to be a "human readable
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string" in the sense that traditional logs are. Instead, the structure is
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optimised for searchability and filtering, with human-understandable log
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keys.
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Args:
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event (dict): The Twisted logging event we are flattening.
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metadata (dict): Additional data to include with each log message. This
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can be information like the server name. Since the target log
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consumer does not know who we are other than by host IP, this
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allows us to forward through static information.
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include_time (bool): Should we include the `time` key? If False, the
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event time is stripped from the event.
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"""
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new_event = {}
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# If it's a failure, make the new event's log_failure be the traceback text.
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if "log_failure" in event:
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new_event["log_failure"] = event["log_failure"].getTraceback()
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# If it's a warning, copy over a string representation of the warning.
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if "warning" in event:
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new_event["warning"] = str(event["warning"])
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# Stdlib logging events have "log_text" as their human-readable portion,
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# Twisted ones have "log_format". For now, include the log_format, so that
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# context only given in the log format (e.g. what is being logged) is
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# available.
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if "log_text" in event:
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new_event["log"] = event["log_text"]
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else:
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new_event["log"] = event["log_format"]
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# We want to include the timestamp when forwarding over the network, but
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# exclude it when we are writing to stdout. This is because the log ingester
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# (e.g. logstash, fluentd) can add its own timestamp.
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if include_time:
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new_event["time"] = round(event["log_time"], 2)
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# Convert the log level to a textual representation.
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new_event["level"] = event["log_level"].name.upper()
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# Ignore these keys, and do not transfer them over to the new log object.
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# They are either useless (isError), transferred manually above (log_time,
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# log_level, etc), or contain Python objects which are not useful for output
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# (log_logger, log_source).
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keys_to_delete = [
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"isError",
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"log_failure",
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"log_format",
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"log_level",
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"log_logger",
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"log_source",
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"log_system",
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"log_time",
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"log_text",
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"observer",
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"warning",
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]
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# If it's from the Twisted legacy logger (twisted.python.log), it adds some
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# more keys we want to purge.
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if event.get("log_namespace") == "log_legacy":
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keys_to_delete.extend(["message", "system", "time"])
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# Rather than modify the dictionary in place, construct a new one with only
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# the content we want. The original event should be considered 'frozen'.
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for key in event.keys():
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if key in keys_to_delete:
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continue
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if isinstance(event[key], (str, int, bool, float)) or event[key] is None:
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# If it's a plain type, include it as is.
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new_event[key] = event[key]
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else:
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# If it's not one of those basic types, write out a string
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# representation. This should probably be a warning in development,
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# so that we are sure we are only outputting useful data.
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new_event[key] = str(event[key])
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# Add the metadata information to the event (e.g. the server_name).
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new_event.update(metadata)
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return new_event
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def TerseJSONToConsoleLogObserver(outFile: IO[str], metadata: dict) -> FileLogObserver:
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"""
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A log observer that formats events to a flattened JSON representation.
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Args:
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outFile: The file object to write to.
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metadata: Metadata to be added to each log object.
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"""
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def formatEvent(_event: dict) -> str:
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flattened = flatten_event(_event, metadata)
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return _encoder.encode(flattened) + "\n"
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return FileLogObserver(outFile, formatEvent)
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@attr.s
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@implementer(IPushProducer)
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class LogProducer(object):
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"""
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An IPushProducer that writes logs from its buffer to its transport when it
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is resumed.
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Args:
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buffer: Log buffer to read logs from.
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transport: Transport to write to.
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"""
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transport = attr.ib(type=ITransport)
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_buffer = attr.ib(type=deque)
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_paused = attr.ib(default=False, type=bool, init=False)
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def pauseProducing(self):
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self._paused = True
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def stopProducing(self):
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self._paused = True
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self._buffer = deque()
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def resumeProducing(self):
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self._paused = False
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while self._paused is False and (self._buffer and self.transport.connected):
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try:
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event = self._buffer.popleft()
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self.transport.write(_encoder.encode(event).encode("utf8"))
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self.transport.write(b"\n")
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except Exception:
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# Something has gone wrong writing to the transport -- log it
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# and break out of the while.
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traceback.print_exc(file=sys.__stderr__)
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break
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@attr.s
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@implementer(ILogObserver)
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class TerseJSONToTCPLogObserver(object):
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"""
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An IObserver that writes JSON logs to a TCP target.
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Args:
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hs (HomeServer): The homeserver that is being logged for.
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host: The host of the logging target.
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port: The logging target's port.
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metadata: Metadata to be added to each log entry.
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"""
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hs = attr.ib()
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host = attr.ib(type=str)
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port = attr.ib(type=int)
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metadata = attr.ib(type=dict)
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maximum_buffer = attr.ib(type=int)
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_buffer = attr.ib(default=attr.Factory(deque), type=deque)
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_connection_waiter = attr.ib(default=None, type=Optional[Deferred])
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_logger = attr.ib(default=attr.Factory(Logger))
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_producer = attr.ib(default=None, type=Optional[LogProducer])
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def start(self) -> None:
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# Connect without DNS lookups if it's a direct IP.
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try:
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ip = ip_address(self.host)
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if isinstance(ip, IPv4Address):
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endpoint = TCP4ClientEndpoint(
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self.hs.get_reactor(), self.host, self.port
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)
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elif isinstance(ip, IPv6Address):
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endpoint = TCP6ClientEndpoint(
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self.hs.get_reactor(), self.host, self.port
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)
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except ValueError:
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endpoint = HostnameEndpoint(self.hs.get_reactor(), self.host, self.port)
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factory = Factory.forProtocol(Protocol)
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self._service = ClientService(endpoint, factory, clock=self.hs.get_reactor())
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self._service.startService()
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self._connect()
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def stop(self):
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self._service.stopService()
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def _connect(self) -> None:
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"""
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Triggers an attempt to connect then write to the remote if not already writing.
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"""
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if self._connection_waiter:
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return
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self._connection_waiter = self._service.whenConnected(failAfterFailures=1)
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@self._connection_waiter.addErrback
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def fail(r):
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r.printTraceback(file=sys.__stderr__)
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self._connection_waiter = None
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self._connect()
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@self._connection_waiter.addCallback
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def writer(r):
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# We have a connection. If we already have a producer, and its
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# transport is the same, just trigger a resumeProducing.
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if self._producer and r.transport is self._producer.transport:
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self._producer.resumeProducing()
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self._connection_waiter = None
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return
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# If the producer is still producing, stop it.
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if self._producer:
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self._producer.stopProducing()
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# Make a new producer and start it.
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self._producer = LogProducer(buffer=self._buffer, transport=r.transport)
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r.transport.registerProducer(self._producer, True)
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self._producer.resumeProducing()
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self._connection_waiter = None
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def _handle_pressure(self) -> None:
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"""
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Handle backpressure by shedding events.
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The buffer will, in this order, until the buffer is below the maximum:
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- Shed DEBUG events
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- Shed INFO events
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- Shed the middle 50% of the events.
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"""
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if len(self._buffer) <= self.maximum_buffer:
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return
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# Strip out DEBUGs
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self._buffer = deque(
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filter(lambda event: event["level"] != "DEBUG", self._buffer)
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)
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if len(self._buffer) <= self.maximum_buffer:
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return
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# Strip out INFOs
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self._buffer = deque(
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filter(lambda event: event["level"] != "INFO", self._buffer)
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)
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if len(self._buffer) <= self.maximum_buffer:
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return
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# Cut the middle entries out
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buffer_split = floor(self.maximum_buffer / 2)
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old_buffer = self._buffer
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self._buffer = deque()
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for i in range(buffer_split):
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self._buffer.append(old_buffer.popleft())
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end_buffer = []
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for i in range(buffer_split):
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end_buffer.append(old_buffer.pop())
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self._buffer.extend(reversed(end_buffer))
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def __call__(self, event: dict) -> None:
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flattened = flatten_event(event, self.metadata, include_time=True)
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self._buffer.append(flattened)
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# Handle backpressure, if it exists.
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try:
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self._handle_pressure()
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except Exception:
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# If handling backpressure fails,clear the buffer and log the
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# exception.
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self._buffer.clear()
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self._logger.failure("Failed clearing backpressure")
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# Try and write immediately.
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self._connect()
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