graph TD
Logger --> Filter
Logger --> Handler
Handler --> Filter
Handler --> Formatter

WARNING :  root        : warn message
日志级别 : Logger实例名称 : 日志消息内容

import logging

logging.basicConfig(filename="test.log", filemode="w", format="%(asctime)s %(name)s:%(levelname)s:%(message)s", datefmt="%d-%M-%Y %H:%M:%S", level=logging.DEBUG)
logging.debug('This is a debug message')
logging.info('This is an info message')
logging.warning('This is a warning message')
logging.error('This is an error message')
logging.critical('This is a critical message')

>>>
13-10-18 21:10:32 root:DEBUG:This is a debug message
13-10-18 21:10:32 root:INFO:This is an info message
13-10-18 21:10:32 root:WARNING:This is a warning message
13-10-18 21:10:32 root:ERROR:This is an error message
13-10-18 21:10:32 root:CRITICAL:This is a critical message

import logging

logging.basicConfig(filename="test.log", filemode="w", format="%(asctime)s %(name)s:%(levelname)s:%(message)s", datefmt="%d-%M-%Y %H:%M:%S", level=logging.DEBUG)
a = 5
b = 0
try:
    c = a / b
except Exception as e:
    # 下面三种方式三选一，推荐使用第一种
    logging.exception("Exception occurred")
    logging.error("Exception occurred", exc_info=True)
    logging.log(level=logging.DEBUG, msg="Exception occurred", exc_info=True)

import logging
import logging.handlers

logger = logging.getLogger("logger")

handler1 = logging.StreamHandler()
handler2 = logging.FileHandler(filename="test.log")

logger.setLevel(logging.DEBUG)
handler1.setLevel(logging.WARNING)
handler2.setLevel(logging.DEBUG)

formatter = logging.Formatter("%(asctime)s %(name)s %(levelname)s %(message)s")
handler1.setFormatter(formatter)
handler2.setFormatter(formatter)

logger.addHandler(handler1)
logger.addHandler(handler2)

# 分别为 10、30、30
# print(handler1.level)
# print(handler2.level)
# print(logger.level)

logger.debug('This is a customer debug message')
logger.info('This is an customer info message')
logger.warning('This is a customer warning message')
logger.error('This is an customer error message')
logger.critical('This is a customer critical message')


>>> 控制台输出
2018-10-13 23:24:57,832 logger WARNING This is a customer warning message
2018-10-13 23:24:57,832 logger ERROR This is an customer error message
2018-10-13 23:24:57,832 logger CRITICAL This is a customer critical message

>>> 文件中输出
2018-10-13 23:44:59,817 logger DEBUG This is a customer debug message
2018-10-13 23:44:59,817 logger INFO This is an customer info message
2018-10-13 23:44:59,817 logger WARNING This is a customer warning message
2018-10-13 23:44:59,817 logger ERROR This is an customer error message
2018-10-13 23:44:59,817 logger CRITICAL This is a customer critical message

logger = logging.getLogger(logger_name)
logger.setLevel(logging.ERROR) # 设置日志级别为ERROR，即只有日志级别大于等于ERROR的日志才会输出
logger.addHandler(handler_name) # 为Logger实例增加一个处理器
logger.removeHandler(handler_name) # 为Logger实例删除一个处理器

import logging.config

config = {
    'version': 1,
    'formatters': {
        'simple': {
            'format': '%(asctime)s - %(name)s - %(levelname)s - %(message)s',
        },
        # 其他的 formatter
    },
    'handlers': {
        'console': {
            'class': 'logging.StreamHandler',
            'level': 'DEBUG',
            'formatter': 'simple'
        },
        'file': {
            'class': 'logging.FileHandler',
            'filename': 'logging.log',
            'level': 'DEBUG',
            'formatter': 'simple'
        },
        # 其他的 handler
    },
    'loggers':{
        'StreamLogger': {
            'handlers': ['console'],
            'level': 'DEBUG',
        },
        'FileLogger': {
            # 既有 console Handler，还有 file Handler
            'handlers': ['console', 'file'],
            'level': 'DEBUG',
        },
        # 其他的 Logger
    }
}

logging.config.dictConfig(config)
StreamLogger = logging.getLogger("StreamLogger")
FileLogger = logging.getLogger("FileLogger")
# 省略日志输出

[loggers]
keys=root,sampleLogger

[handlers]
keys=consoleHandler

[formatters]
keys=sampleFormatter

[logger_root]
level=DEBUG
handlers=consoleHandler

[logger_sampleLogger]
level=DEBUG
handlers=consoleHandler
qualname=sampleLogger
propagate=0

[handler_consoleHandler]
class=StreamHandler
level=DEBUG
formatter=sampleFormatter
args=(sys.stdout,)

[formatter_sampleFormatter]
format=%(asctime)s - %(name)s - %(levelname)s - %(message)s

import logging.config

logging.config.fileConfig(fname='test.ini', disable_existing_loggers=False)
logger = logging.getLogger("sampleLogger")
# 省略日志输出

version: 1
formatters:
  simple:
    format: '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
handlers:
  console:
    class: logging.StreamHandler
    level: DEBUG
    formatter: simple

loggers:
  simpleExample:
    level: DEBUG
    handlers: [console]
    propagate: no
root:
  level: DEBUG
  handlers: [console]

import logging.config
# 需要安装 pyymal 库
import yaml

with open('test.yaml', 'r') as f:
    config = yaml.safe_load(f.read())
    logging.config.dictConfig(config)

logger = logging.getLogger("sampleLogger")
# 省略日志输出

ch.setLevel(logging.WARN) # 指定日志级别，低于WARN级别的日志将被忽略
ch.setFormatter(formatter_name) # 设置一个格式化器formatter
ch.addFilter(filter_name) # 增加一个过滤器，可以增加多个
ch.removeFilter(filter_name) # 删除一个过滤器

sh = logging.StreamHandler(stream=None)

fh = logging.FileHandler(filename, mode='a', encoding=None, delay=False)

filter = logging.Filter(name='')

formatter = logging.Formatter(fmt=None, datefmt=None)

# 自定义 Logger 配置
handler = logging.FileHandler(filename="test.log", encoding="utf-8")


# 使用默认的 Logger 配置
logging.basicConfig(handlers=[logging.FileHandler("test.log", encoding="utf-8")], level=logging.DEBUG)
复制代码

logging.disable(logging.INFO)

logger.disabled = True

# TimedRotatingFileHandler 类构造函数
def __init__(self, filename, when='h', interval=1, backupCount=0, encoding=None, delay=False, utc=False, atTime=None):


# RotatingFileHandler 类的构造函数
def __init__(self, filename, mode='a', maxBytes=0, backupCount=0, encoding=None, delay=False)
复制代码

# 每隔 1000 Byte 划分一个日志文件，备份文件为 3 个
file_handler = logging.handlers.RotatingFileHandler("test.log", mode="w", maxBytes=1000, backupCount=3, encoding="utf-8")


# 每隔 1小时 划分一个日志文件，interval 是时间间隔，备份文件为 10 个
handler2 = logging.handlers.TimedRotatingFileHandler("test.log", when="H", interval=1, backupCount=10)
复制代码

'''
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))

DEFAULT_DATETIME_FORMAT = "%Y-%m-%d %H:%M:%S"
DEFAULT_LOG_FORMAT = "%(asctime)s [%(module)s.%(funcName)s.%(lineno)d] - %(levelname)s - %(message)s"


def get_logger(
    logger_name,
    log_level=logging.INFO,
    log_format=DEFAULT_LOG_FORMAT
):
    logger = logging.getLogger(logger_name)
    logger.setLevel(log_level)
    ch = logging.StreamHandler()
    formatter = JsonFormatter(log_format, DEFAULT_DATETIME_FORMAT)
    ch.setFormatter(formatter)
    if not logger.handlers:
        logger.addHandler(ch)
    return logger


logger = get_logger(__name__)

[loggers]
keys=root, gunicorn.error, gunicorn.access

[handlers]
keys=console

[formatters]
keys=json

[logger_root]
level=INFO
handlers=console

[logger_gunicorn.error]
level=ERROR
handlers=console
propagate=0
qualname=gunicorn.error

[handler_console]
class=StreamHandler
level=INFO
formatter=json
args=(sys.stdout, )

[formatter_json]
class=bdp_service.common.json_logger.JsonFormatter

[logger_gunicorn.access]
level=INFO
handlers=console
propagate=0
qualname=gunicorn.access

gunicorn,-w,6,-b:6000,-k,gevent,-t,3600,--access-logfile,-,--access-logformat,%({X-Forwarded-For}i)s %(t)s %(u)s %(U)s %(a)s %(h)s %(m)s %(q)s %(s)s %(b)s,--graceful-timeout,3600,--log-config,gunicorn_logging.conf,service_repo.api.app:app