import logging
logging.debug('debug message')
logging.info('info message')
logging.warning('warning message')

import os

logging.basicConfig(
  filename=os.path.join(os.getcwd(),'all.log'),
  level=logging.DEBUG,
  format='%(asctime)s %(filename)s : %(levelname)s %(message)s', # 定义输出log的格式
  filemode='a',
  datefmt='%Y-%m-%d %A %H:%M:%S',
)

logging.debug('this is a message')

import logging
from logging import handlers


class Logger(object):
  level_relations = {
    'debug': logging.DEBUG,
    'info': logging.INFO,
    'warning': logging.WARNING,
    'error': logging.ERROR,
    'crit': logging.CRITICAL
  }

  def __init__(self, filename, level='info', when='D', backCount=3,
         fmt='%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s'):
    self.logger = logging.getLogger(filename)
    format_str = logging.Formatter(fmt) # 设置日志格式
    self.logger.setLevel(self.level_relations.get(level)) # 设置日志级别

    # 向控制台输出日志
    stream_handler = logging.StreamHandler()
    stream_handler.setFormatter(format_str)
    self.logger.addHandler(stream_handler)

    # 日志按文件大小写入文件
    # 1MB = 1024 * 1024 bytes
    # 这里设置文件的大小为500MB
    rotating_file_handler = handlers.RotatingFileHandler(
      filename=filename, mode='a', maxBytes=1024 * 1024 * 500, backupCount=5, encoding='utf-8')
    rotating_file_handler.setFormatter(format_str)
    self.logger.addHandler(rotating_file_handler)


log = Logger('all.log', level='info')

log.logger.info('[测试log] hello, world')

import logging
from logging import handlers


class Logger(object):
  level_relations = {
    'debug': logging.DEBUG,
    'info': logging.INFO,
    'warning': logging.WARNING,
    'error': logging.ERROR,
    'crit': logging.CRITICAL
  }

  def __init__(self, filename, level='info', when='D', backCount=3,
         fmt='%(asctime)s - %(pathname)s[line:%(lineno)d] - %(levelname)s: %(message)s'):
    self.logger = logging.getLogger(filename)
    format_str = logging.Formatter(fmt) # 设置日志格式
    self.logger.setLevel(self.level_relations.get(level)) # 设置日志级别

    # 往文件里写入
    # 指定间隔时间自动生成文件的处理器
    timed_rotating_file_handler = handlers.TimedRotatingFileHandler(
      filename=filename, when=when, backupCount=backCount, encoding='utf-8')

    # 实例化TimedRotatingFileHandler
    # interval是时间间隔，backupCount是备份文件的个数，如果超过这个个数，就会自动删除，when是间隔的时间单位，单位有以下几种：
    # S 秒
    # M 分
    # H 小时、
    # D 天、
    # W 每星期（interval==0时代表星期一）
    # midnight 每天凌晨
    timed_rotating_file_handler.setFormatter(format_str) # 设置文件里写入的格式
    self.logger.addHandler(timed_rotating_file_handler)

    # 往屏幕上输出
    stream_handler = logging.StreamHandler()
    stream_handler.setFormatter(format_str)
    self.logger.addHandler(stream_handler)


log = Logger('all.log', level='info')
log.logger.info('[测试log] hello, world')

.
├── apps_api
│  ├── common
│  ├── models
│  └── resources
├── logs
├── migrations
│  └── versions
├── static
├── templates
├── test
└── utils
└── app.py
└── config.py
└── exts.py
└── log.py
└── manage.py
└── run.py
└── README.md
└── requirements.txt

# -*- coding: utf-8 -*-

import logging
from flask.logging import default_handler
import os

from logging.handlers import RotatingFileHandler
from logging import StreamHandler

BASE_DIR = os.path.dirname(os.path.abspath(__file__))

LOG_PATH = os.path.join(BASE_DIR, 'logs')

LOG_PATH_ERROR = os.path.join(LOG_PATH, 'error.log')
LOG_PATH_INFO = os.path.join(LOG_PATH, 'info.log')
LOG_PATH_ALL = os.path.join(LOG_PATH, 'all.log')

# 日志文件最大 100MB
LOG_FILE_MAX_BYTES = 100 * 1024 * 1024
# 轮转数量是 10 个
LOG_FILE_BACKUP_COUNT = 10


class Logger(object):

  def init_app(self, app):
        # 移除默认的handler
    app.logger.removeHandler(default_handler)

    formatter = logging.Formatter(
      '%(asctime)s [%(thread)d:%(threadName)s] [%(filename)s:%(module)s:%(funcName)s] '
      '[%(levelname)s]: %(message)s'
    )

    # 将日志输出到文件
    # 1 MB = 1024 * 1024 bytes
    # 此处设置日志文件大小为500MB，超过500MB自动开始写入新的日志文件，历史文件归档
    file_handler = RotatingFileHandler(
      filename=LOG_PATH_ALL,
      mode='a',
      maxBytes=LOG_FILE_MAX_BYTES,
      backupCount=LOG_FILE_BACKUP_COUNT,
      encoding='utf-8'
    )

    file_handler.setFormatter(formatter)
    file_handler.setLevel(logging.INFO)

    stream_handler = StreamHandler()
    stream_handler.setFormatter(formatter)
    stream_handler.setLevel(logging.INFO)

    for logger in (
        # 这里自己还可以添加更多的日志模块，具体请参阅Flask官方文档
        app.logger,
        logging.getLogger('sqlalchemy'),
        logging.getLogger('werkzeug')

    ):
      logger.addHandler(file_handler)
      logger.addHandler(stream_handler)

# encoding: utf-8
from log import Logger

logger = Logger()

# encoding: utf-8
from flask import Flask
from config import CONFIG
from exts import logger


def create_app():
  app = Flask(__name__)

  # 加载配置
  app.config.from_object(CONFIG)

    # 初始化logger
  logger.init_app(app)

  return app

# -*- coding: utf-8 -*-

from app import create_app

app = create_app()

if __name__ == '__main__':
  app.run()

$ python run.py
* Serving Flask app "app" (lazy loading)
* Environment: production
  WARNING: This is a development server. Do not use it in a production deployment.
  Use a production WSGI server instead.
* Debug mode: on
2019-07-08 08:15:50,396 [140735687508864:MainThread] [_internal.py:_internal:_log] [INFO]: * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
2019-07-08 08:15:50,397 [140735687508864:MainThread] [_internal.py:_internal:_log] [INFO]: * Restarting with stat
2019-07-08 08:15:50,748 [140735687508864:MainThread] [_internal.py:_internal:_log] [WARNING]: * Debugger is active!
2019-07-08 08:15:50,755 [140735687508864:MainThread] [_internal.py:_internal:_log] [INFO]: * Debugger PIN: 234-828-739