python-json-logger/src/pythonjsonlogger/jsonlogger.py at master · doselect/python-json-logger · GitHub

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'''

This library is provided to allow standard python logging

to output log data as JSON formatted strings

'''

import logging

import json

import re

from datetime import date, datetime, time

import traceback

import importlib

from inspect import istraceback

from collections import OrderedDict

# skip natural LogRecord attributes

# http://docs.python.org/library/logging.html#logrecord-attributes

RESERVED_ATTRS = (

'args', 'asctime', 'created', 'exc_info', 'exc_text', 'filename',

'funcName', 'levelname', 'levelno', 'lineno', 'module',

'msecs', 'message', 'msg', 'name', 'pathname', 'process',

'processName', 'relativeCreated', 'stack_info', 'thread', 'threadName')

def merge_record_extra(record, target, reserved):

"""

Merges extra attributes from LogRecord object into target dictionary

:param record: logging.LogRecord

:param target: dict to update

:param reserved: dict or list with reserved keys to skip

"""

for key, value in record.__dict__.items():

# this allows to have numeric keys

if (key not in reserved

and not (hasattr(key, "startswith")

and key.startswith('_'))):

target[key] = value

return target

class JsonEncoder(json.JSONEncoder):

"""

A custom encoder extending the default JSONEncoder

"""

def default(self, obj):

if isinstance(obj, (date, datetime, time)):

return self.format_datetime_obj(obj)

elif istraceback(obj):

return ''.join(traceback.format_tb(obj)).strip()

elif type(obj) == Exception \

or isinstance(obj, Exception) \

or type(obj) == type:

return str(obj)

try:

return super(JsonEncoder, self).default(obj)

except TypeError:

try:

return str(obj)

except Exception:

return None

def format_datetime_obj(self, obj):

return obj.isoformat()

class JsonFormatter(logging.Formatter):

"""

A custom formatter to format logging records as json strings.

Extra values will be formatted as str() if not supported by

json default encoder

"""

def __init__(self, *args, **kwargs):

"""

:param json_default: a function for encoding non-standard objects

as outlined in http://docs.python.org/2/library/json.html

:param json_encoder: optional custom encoder

:param json_serializer: a :meth:`json.dumps`-compatible callable

that will be used to serialize the log record.

:param json_indent: an optional :meth:`json.dumps`-compatible numeric value

that will be used to customize the indent of the output json.

:param prefix: an optional string prefix added at the beginning of

the formatted string

:param json_indent: indent parameter for json.dumps

:param json_ensure_ascii: ensure_ascii parameter for json.dumps

:param reserved_attrs: an optional list of fields that will be skipped when

outputting json log record. Defaults to all log record attributes:

http://docs.python.org/library/logging.html#logrecord-attributes

:param timestamp: an optional string/boolean field to add a timestamp when

outputting the json log record. If string is passed, timestamp will be added

to log record using string as key. If True boolean is passed, timestamp key

will be "timestamp". Defaults to False/off.

"""

self.json_default = self._str_to_fn(kwargs.pop("json_default", None))

self.json_encoder = self._str_to_fn(kwargs.pop("json_encoder", None))

self.json_serializer = self._str_to_fn(kwargs.pop("json_serializer", json.dumps))

self.json_indent = kwargs.pop("json_indent", None)

self.json_ensure_ascii = kwargs.pop("json_ensure_ascii", True)

self.prefix = kwargs.pop("prefix", "")

reserved_attrs = kwargs.pop("reserved_attrs", RESERVED_ATTRS)

self.reserved_attrs = dict(zip(reserved_attrs, reserved_attrs))

self.timestamp = kwargs.pop("timestamp", False)

# super(JsonFormatter, self).__init__(*args, **kwargs)

logging.Formatter.__init__(self, *args, **kwargs)

if not self.json_encoder and not self.json_default:

self.json_encoder = JsonEncoder

self._required_fields = self.parse()

self._skip_fields = dict(zip(self._required_fields,

self._required_fields))

self._skip_fields.update(self.reserved_attrs)

def _str_to_fn(self, fn_as_str):

"""

If the argument is not a string, return whatever was passed in.

Parses a string such as package.module.function, imports the module

and returns the function.

:param fn_as_str: The string to parse. If not a string, return it.

"""

if not isinstance(fn_as_str, str):

return fn_as_str

path, _, function = fn_as_str.rpartition('.')

module = importlib.import_module(path)

return getattr(module, function)

def parse(self):

"""

Parses format string looking for substitutions

This method is responsible for returning a list of fields (as strings)

to include in all log messages.

"""

standard_formatters = re.compile(r'\((.+?)\)', re.IGNORECASE)

return standard_formatters.findall(self._fmt)

def add_fields(self, log_record, record, message_dict):

"""

Override this method to implement custom logic for adding fields.

"""

for field in self._required_fields:

log_record[field] = record.__dict__.get(field)

log_record.update(message_dict)

merge_record_extra(record, log_record, reserved=self._skip_fields)

if self.timestamp:

key = self.timestamp if type(self.timestamp) == str else 'timestamp'

log_record[key] = datetime.utcnow()

def process_log_record(self, log_record):

"""

Override this method to implement custom logic

on the possibly ordered dictionary.

"""

return log_record

def jsonify_log_record(self, log_record):

"""Returns a json string of the log record."""

return self.json_serializer(log_record,

default=self.json_default,

cls=self.json_encoder,

indent=self.json_indent,

ensure_ascii=self.json_ensure_ascii)

def format(self, record):

"""Formats a log record and serializes to json"""

message_dict = {}

if isinstance(record.msg, dict):

message_dict = record.msg

record.message = None

else:

record.message = record.getMessage()

# only format time if needed

if "asctime" in self._required_fields:

record.asctime = self.formatTime(record, self.datefmt)

# Display formatted exception, but allow overriding it in the

# user-supplied dict.

if record.exc_info and not message_dict.get('exc_info'):

message_dict['exc_info'] = self.formatException(record.exc_info)

if not message_dict.get('exc_info') and record.exc_text:

message_dict['exc_info'] = record.exc_text

# Display formatted record of stack frames

# default format is a string returned from :func:`traceback.print_stack`

try:

if record.stack_info and not message_dict.get('stack_info'):

message_dict['stack_info'] = self.formatStack(record.stack_info)

except AttributeError:

# Python2.7 doesn't have stack_info.

pass

try:

log_record = OrderedDict()

except NameError:

log_record = {}

self.add_fields(log_record, record, message_dict)

log_record = self.process_log_record(log_record)

return "%s%s" % (self.prefix, self.jsonify_log_record(log_record))

python-json-logger/src/pythonjsonlogger/jsonlogger.py at master · doselect/python-json-logger · GitHub

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