How to configure YAML to create fresh log files instead of appending them?
<p>In a python logger implementation given below, each time I run my program, the logs are <em>appended</em> each time to the existing log files. How do I ensure that each time I run my application code, they are written to the fresh log file? </p>

<p>Is it happening because I have set the RotatingFileHandler with backup count as 20 with each file size of 10MB? Should I convert it to simple file handler? </p>

<p>I am using following yaml based log configuration in my python logger. </p>

<pre><code>  1 version: 1
  2
  3 formatters:
  4   simple:
  5     format: '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
  6
  7 handlers:
  8   console:
  9     class: logging.StreamHandler
 10     level: DEBUG
 11     formatter: simple
 12     stream: ext://sys.stdout
 13
 14   info_handler:
 15     class: logging.handlers.RotatingFileHandler
 16     level: INFO
 17     formatter: simple
 18     filename: info.log
 19     maxBytes: 10485760 # 10MB
 20     backupCount: 20
 21     encoding: utf8
 22
 23   error_handler:
 24     class: logging.handlers.RotatingFileHandler
 25     level: ERROR
 26     formatter: simple
 27     filename: errors.log
 28     maxBytes: 10485760 # 10MB
 29     backupCount: 20
 30     encoding: utf8
 31
 32 loggers:
 33   my_module:
 34     level: ERROR
 35     handlers: [console]
 36     propagate: no
 37
 38 root:
 39   level: DEBUG
 40   handlers: [info_handler, info_handler]
</code></pre>

<p>I am using the following python logger initializer code to initialize my logger. </p>

<pre><code>  1 import os
  2 import logging.config
  3 import yaml
  4
  5 """Setup logging configuration """
  6 default_path='logging.yaml'
  7 default_level=logging.INFO
  8 env_key='LOG_CFG'
  9
 10 class MyLogger():
 11
 12     def __init__(self):
 13         path = default_path
 14         value = os.getenv(env_key, None)
 15         if value:
 16             path = value
 17         if os.path.exists(path):
 18             with open(path, 'rt') as f:
 19                 config = yaml.safe_load(f.read())
 20             logging.config.dictConfig(config)
 21         else:
 22             logging.basicConfig(filemode='w', level=default_level)
</code></pre>

<p>Set the <a href="https://docs.python.org/3.5/library/logging.html#logging.basicConfig" rel="nofollow"><code>filemode</code></a> to <code>w</code>, the default is <code>a</code> (append). </p>

<p>Or alternatively just add the following line to overwrite your old log file (after reading the yaml file):</p>

<pre><code>with open(config['handlers']['info_handler']['filename'], 'w') as f:
    pass
</code></pre>

python pyyaml