How to change date format for Django logging?

Question

The comments in the answer here say that you should be able to customize the date format for logging in Django:

Note that if you're using the dictConfig method of configuring logging (e.g. if you're using Django), you can set this using the 'datefmt' dict key for a formatter. See: Django Logging Configuration , logging module: Dictionary Schema Details

However, it does not work:

# settings.py
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'django.server': { # duplicate of default for django.server
            '()': 'django.utils.log.ServerFormatter',
            'format': '[{server_time}] {message}',
            'style': '{',
            'datefmt' : '%Y-%m-%d %H:%M:%S'
            }
}

This does not work either:

# settings.py
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'default': {
            'datefmt' : '%Y-%m-%d %H:%M:%S'
            },
}

In both cases, I still get the default logging date format:

[13/Mar/2019 21:53:05] "GET / HTTP/1.1" 200 16808

Note that in the source code, the datefmt should have been passed on and used, but it appears that this is not the case:

https://github.com/django/django/blob/782d85b6dfa191e67c0f1d572641d8236c79174c/django/utils/log.py#L190

Using Python 3.6 and Django 2.1

---

Update:

When I include this in my settings.py as described:

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'django.server': {
            '()': 'django.utils.log.ServerFormatter',
            'format': '[{server_time}] {message}',
            'datefmt' : '%Y-%m-%d %H:%M:%S',
            'style': '{',
        }
}

And then edit the file conda//lib/python3.6/site-packages/django/utils/log.py like this:

class ServerFormatter(logging.Formatter):
    def __init__(self, *args, **kwargs):
        self.style = color_style()
        super().__init__(*args, **kwargs)
        print("self.datefmt", self.datefmt)

I get messages in my console that look like this, indicating that I actually am propagating the datefmt correctly:

$ python manage.py runserver
self.datefmt %Y-%m-%d %H:%M:%S
self.datefmt %Y-%m-%d %H:%M:%S
Performing system checks...

System check identified no issues (0 silenced).
March 13, 2019 - 23:43:50
Django version 2.1.2, using settings 'webapp.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
[13/Mar/2019 23:45:14] "GET / HTTP/1.1" 200 16808

Maybe the error has to do with this line in django/utils/log.py?

if self.uses_server_time() and not hasattr(record, 'server_time'):
            record.server_time = self.formatTime(record, self.datefmt)

^ No matter what I do, it appears that this check never gets tripped, because not hasattr(record, 'server_time') always evaluates to False, because record already has server_time by default, and it appears to come from this section of Django code in django/core/servers/basehttp.py:

class WSGIRequestHandler(simple_server.WSGIRequestHandler):
...
...
    def log_message(self, format, *args):
        extra = {
            'request': self.request,
            'server_time': self.log_date_time_string(),
        }

Where simple_server.WSGIRequestHandler.log_date_time_string() is coming from the wsgiref package. However, that package does not contain any reference to the function log_date_time_string(), it appears to be coming directly from the Python builtin http library (conda//lib/python3.6/http/server.py):

def log_date_time_string(self):
    """Return the current time formatted for logging."""
    now = time.time()
    year, month, day, hh, mm, ss, x, y, z = time.localtime(now)
    s = "%02d/%3s/%04d %02d:%02d:%02d" % (
            day, self.monthname[month], year, hh, mm, ss)
    return s

^ The date format here is hard-coded into the library, does not appear to be changeable.

So... how is any of this supposed to work? Am I missing something? Is this some sort of bug in Django? Unless I am mistaken there is no way to override this datefmt based on this?

Answer 1

That was a good, detailed investigation. Make sure that your research includes the Django ticket tracker. The first hit on a search for site:code.djangoproject.com datefmt reveals that this is a known bug.

That ticket shows a possible workaround—use asctime instead of server_time.