ansible.cfg file hijack my django project log file output path - django

Question

I have a strange django log file output problem, I use the ansible 2.5.0 module in my django 1.11.11 project like this from ansible.plugins.callback import CallbackBase, and the log_path setting in the /etc/ansible/ansible.cfg file actually takes effect for my django project log file output, like a hijack:
# /etc/ansible/ansible.cfg file
# logging is off by default unless this path is defined
# if so defined, consider logrotate
log_path = /var/log/ansible.log
All my django log output to the /var/log/ansible.log which is quite odd
# /var/log/ansible.log
2019-01-07 17:49:22,271 django.server "GET /docs/ HTTP/1.1" 200 1391207
2019-01-07 17:49:23,262 django.server "GET /docs/schema.js HTTP/1.1" 200 111440
I did set up the LOGGING in my django settings, the django setting takes effect too, and the output is like this:
# /var/log/django_debug.log
"GET /docs/ HTTP/1.1" 200 1391207
"GET /docs/schema.js HTTP/1.1" 200 111440
It will be two log files for the same django project in same log level I defined in the django settings:
# django settings.py
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'handlers': {
'file': {
'level': 'INFO',
'class': 'logging.FileHandler',
'filename': '/var/log/django_debug.log',
},
},
'loggers': {
'django': {
'handlers': ['file'],
'level': 'INFO',
'propagate': True,
},
},
}

Answer 1

Did you import Ansible as a Python module by any chance?
TLDR: When you import Ansible as a module, the logger instance inside Ansible lib gets instantiated first and you end up using Ansible's logger, unless you set disable_existing_loggers to True.
Why this happens?
Python logging is a singleton, which means that only one object of logger can exist in the memory in given process.
Libraries (such as Ansible) can also use loggers internally. In my case, the Ansible's logger was instantiated somewhere in the Ansible global scope. https://github.com/ansible/ansible/blob/devel/lib/ansible/utils/display.py#L65
When you import library, the logger is already instantiated, so your own logger will inherit the existing log handler and you'll end up writing logs to both log files.
What to do to prevent this?
Please try switching the disable_existing_loggers setting to True.
Django docs for logging: https://docs.djangoproject.com/en/2.1/topics/logging/#configuring-logging
Analogical settings for Python logger itself: https://docs.python.org/3/library/logging.config.html?highlight=disable_existing_loggers#logging.config.fileConfig
One note for my case: I used logging.handlers.WatchedFileHandler which seems to inherit previous loggers by default.
Please give feedback if this fixed your problem!