115 lines
3.7 KiB
Python
115 lines
3.7 KiB
Python
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#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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from __future__ import absolute_import
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import datetime
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import json
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import logging
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import re
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import traceback
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LOG_FORMAT_REGEXP = re.compile(r'\((.+?)\)', re.IGNORECASE)
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def _json_default(obj):
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"""
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Coerce everything to strings.
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All objects representing time get output as ISO8601.
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"""
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if isinstance(obj, (datetime.date, datetime.time, datetime.datetime)):
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return obj.isoformat()
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elif isinstance(obj, Exception):
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return "Exception: %s" % str(obj)
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return str(obj)
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# skip natural LogRecord attributes
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# http://docs.python.org/library/logging.html#logrecord-attributes
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RESERVED_ATTRS = set([
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'args', 'asctime', 'created', 'exc_info', 'exc_text', 'filename', 'funcName', 'levelname',
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'levelno', 'lineno', 'module', 'msecs', 'message', 'msg', 'name', 'pathname', 'process',
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'processName', 'relativeCreated', 'stack_info', 'thread', 'threadName'
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])
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class JsonFormatter(logging.Formatter):
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"""
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A custom formatter to format logging records as json strings.
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extra values will be formatted as str() if nor supported by
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json default encoder
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"""
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def __init__(self, *args, **kwargs):
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"""
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:param json_default: a function for encoding non-standard objects
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as outlined in http://docs.python.org/2/library/json.html
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:param json_encoder: optional custom encoder
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:param json_serializer: a :meth:`json.dumps`-compatible callable
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that will be used to serialize the log record.
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:param prefix: an optional key prefix to nest logs
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"""
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self.json_default = kwargs.pop("json_default", _json_default)
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self.json_encoder = kwargs.pop("json_encoder", None)
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self.json_serializer = kwargs.pop("json_serializer", json.dumps)
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self.default_values = kwargs.pop("default_extra", {})
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self.prefix_key = kwargs.pop("prefix_key", "data")
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logging.Formatter.__init__(self, *args, **kwargs)
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self._fmt_parameters = self._parse_format_string()
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self._skip_fields = set(self._fmt_parameters)
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self._skip_fields.update(RESERVED_ATTRS)
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def _parse_format_string(self):
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"""Parses format string looking for substitutions"""
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standard_formatters = LOG_FORMAT_REGEXP
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return standard_formatters.findall(self._fmt)
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def add_fields(self, log_record, record, message_dict):
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"""
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Override this method to implement custom logic for adding fields.
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"""
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target = log_record
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if self.prefix_key:
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log_record[self.prefix_key] = {}
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target = log_record[self.prefix_key]
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for field, value in record.__dict__.iteritems():
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if field in self._fmt_parameters and field in RESERVED_ATTRS:
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log_record[field] = value
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elif field not in RESERVED_ATTRS:
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target[field] = value
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target.update(message_dict)
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target.update(self.default_values)
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def format(self, record):
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"""Formats a log record and serializes to json"""
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message_dict = {}
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if isinstance(record.msg, dict):
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message_dict = record.msg
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record.message = None
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if "message" in message_dict:
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record.message = message_dict.pop("message", "")
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else:
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record.message = record.getMessage()
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# only format time if needed
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if "asctime" in self._fmt_parameters:
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record.asctime = self.formatTime(record, self.datefmt)
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# Display formatted exception, but allow overriding it in the
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# user-supplied dict.
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if record.exc_info and not message_dict.get('exc_info'):
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message_dict['exc_info'] = traceback.format_list(traceback.extract_tb(record.exc_info[2]))
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log_record = {}
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self.add_fields(log_record, record, message_dict)
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return self.json_serializer(log_record, default=self.json_default, cls=self.json_encoder)
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