logging模块使用

1.基本使用

配置logging基本的设置，然后在控制台输出日志，

import logging

logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(name)s - % 
                    (levelname)s - %(message)s')
logger = logging.getLogger(__name__)

logger.info("Start print log")
logger.debug("Do something")
logger.warning("Something maybe fail.")
logger.info("Finish")

运行时，控制台输出

2018-09-20 19:40:36,677 - __main__ - INFO - Start print log
2018-09-20 19:40:36,677 - __main__ - WARNING - Something maybe fail.
2018-09-20 19:40:36,677 - __main__ - INFO - Finish

2.将日志写入到文件

设置logging，创建一个FileHandler，并对输出消息的格式进行设置，将其添加到logger，然后将日志写入到指定的文件中，

import logging

logger = logging.getLogger(__name__)
logger.setLevel(level = logging.INFO)
handler = logging.FileHandler("log.txt")
handler.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)
logger.addHandler(handler)

logger.info("Start print log")
logger.debug("Do something")
logger.warning("Something maybe fail.")
logger.info("Finish")

log.txt中日志数据为，

2018-09-20 19:44:05,901 - __main__ - INFO - Start print log
2018-09-20 19:44:05,901 - __main__ - WARNING - Something maybe fail.
2018-09-20 19:44:05,901 - __main__ - INFO - Finish

3.将日志同时输出到屏幕和日志文件2.2.2 将日志同时输出到屏幕和日志文件

logger中添加StreamHandler，可以将日志输出到屏幕上

import logging

logger = logging.getLogger(__name__)
logger.setLevel(level=logging.INFO)
handler = logging.FileHandler("log.txt")
handler.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)

console = logging.StreamHandler()
console.setLevel(logging.INFO)

logger.addHandler(handler)
logger.addHandler(console)

logger.info("Start print log")
logger.debug("Do something")
logger.warning("Something maybe fail.")
logger.info("Finish")

控制台中看到，

Start print log
Something maybe fail.
Finish

在log.txt文件中可以看到

2018-09-20 19:47:25,266 - __main__ - INFO - Start print log
2018-09-20 19:47:25,266 - __main__ - WARNING - Something maybe fail.
2018-09-20 19:47:25,266 - __main__ - INFO - Finish

4.多模块使用logging

主模块mainModule.py，

import logging
import subModule
logger = logging.getLogger("mainModule")
logger.setLevel(level = logging.INFO)
handler = logging.FileHandler("log.txt")
handler.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)

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

logger.addHandler(handler)
logger.addHandler(console)


logger.info("creating an instance of subModule.subModuleClass")
a = subModule.SubModuleClass()
logger.info("calling subModule.subModuleClass.doSomething")
a.doSomething()
logger.info("done with  subModule.subModuleClass.doSomething")
logger.info("calling subModule.some_function")
subModule.som_function()
logger.info("done with subModule.some_function")

子模块subModule.py

import logging

module_logger = logging.getLogger("mainModule.sub")
class SubModuleClass(object):
    def __init__(self):
        self.logger = logging.getLogger("mainModule.sub.module")
        self.logger.info("creating an instance in SubModuleClass")
    def doSomething(self):
        self.logger.info("do something in SubModule")
        a = []
        a.append(1)
        self.logger.debug("list a = " + str(a))
        self.logger.info("finish something in SubModuleClass")

def som_function():
    module_logger.info("call function some_function")

执行之后，在控制和日志文件log.txt中输出，

2018-09-20 19:58:21,603 - mainModule - INFO - creating an instance of subModule.subModuleClass
2018-09-20 19:58:21,603 - mainModule.sub.module - INFO - creating an instance in SubModuleClass
2018-09-20 19:58:21,603 - mainModule - INFO - calling subModule.subModuleClass.doSomething
2018-09-20 19:58:21,603 - mainModule.sub.module - INFO - do something in SubModule
2018-09-20 19:58:21,603 - mainModule.sub.module - INFO - finish something in SubModuleClass
2018-09-20 19:58:21,603 - mainModule - INFO - done with  subModule.subModuleClass.doSomething
2018-09-20 19:58:21,603 - mainModule - INFO - calling subModule.some_function
2018-09-20 19:58:21,603 - mainModule.sub - INFO - call function some_function
2018-09-20 19:58:21,603 - mainModule - INFO - done with subModule.some_function

5.通过YAML文件配置

通过YAML文件进行配置，比JSON看起来更加简介明了，

version: 1
disable_existing_loggers: False
formatters:
        simple:
            format: "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
handlers:
    console:
            class: logging.StreamHandler
            level: DEBUG
            formatter: simple
            stream: ext://sys.stdout
    info_file_handler:
            class: logging.handlers.RotatingFileHandler
            level: INFO
            formatter: simple
            filename: info.log
            maxBytes: 10485760
            backupCount: 20
            encoding: utf8
    error_file_handler:
            class: logging.handlers.RotatingFileHandler
            level: ERROR
            formatter: simple
            filename: errors.log
            maxBytes: 10485760
            backupCount: 20
            encoding: utf8
loggers:
    my_module:
            level: ERROR
            handlers: [info_file_handler]
            propagate: no
root:
    level: INFO
    handlers: [console,info_file_handler,error_file_handler]
通过YAML加载配置文件，然后通过logging.dictConfig配置logging，

代码

import yaml
import logging.config
import os


def setup_logging(default_path="logging.yaml", default_level=logging.INFO, env_key="LOG_CFG"):
    path = default_path
    value = os.getenv(env_key, None)
    print('value', value)
    print(os.path.exists(path))
    if value:
        path = value
    if os.path.exists(path):
        with open(path, "r") as f:
            config = yaml.load(f)
            logging.config.dictConfig(config)  # 配置logging
    else:
        logging.basicConfig(level=default_level)


def func():
    logging.info("start func")

    logging.info("exec func")

    logging.info("end func")


if __name__ == "__main__":
    setup_logging(default_path="logging.yaml")
    func()

控制台

('value', None)
True
2018-09-20 20:08:57,523 - root - INFO - start func
2018-09-20 20:08:57,523 - root - INFO - exec func
2018-09-20 20:08:57,523 - root - INFO - end func

inf.log文件

2018-09-20 20:08:57,523 - root - INFO - start func
2018-09-20 20:08:57,523 - root - INFO - exec func
2018-09-20 20:08:57,523 - root - INFO - end func

6.日志回滚

使用RotatingFileHandler，可以实现日志回滚

import logging
from logging.handlers import RotatingFileHandler
logger = logging.getLogger(__name__)
logger.setLevel(level = logging.INFO)
#定义一个RotatingFileHandler，最多备份3个日志文件，每个日志文件最大1K
rHandler = RotatingFileHandler("log.txt",maxBytes = 1*1024,backupCount = 3)
rHandler.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
rHandler.setFormatter(formatter)

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

logger.addHandler(rHandler)
logger.addHandler(console)

logger.info("Start print log")
logger.debug("Do something")
logger.warning("Something maybe fail.")
logger.info("Finish")

可以在工程目录中看到，备份的日志文件，



2016/10/09  19:36               732 log.txt
2016/10/09  19:36               967 log.txt.1
2016/10/09  19:36               985 log.txt.2
2016/10/09  19:36               976 log.txt.3