bes 0.3

Django

Although the core of the library is framework-agnostic, we’ll be using this to log events in a Django website. There are a few helpers for extracting information from HttpRequest to make this as easy as possible. Drop it into your views with somthing like:

import django.http
imort django.shortcuts
import bes.django
from polls.models import Poll

def detail(request, poll_id):
    try:
        p = Poll.objects.get(pk=poll_id)
    except Poll.DoesNotExist:
        bes.django.log_user_request_path(
            request=request, type='404', poll_id=poll_id)
        raise django.http.Http404
    bes.django.log_user_request_path(
        request=request, type='poll-detail',
        poll_id=poll_id, poll_name=p.name)
    return django.shortcutsrender_to_response(
        'polls/detail.html', {'poll': p})

You can also override bes’ defaults in your Django config:

BULK_ELASTIC_SEARCH_LOGGING_HOST = 'my-es-server.example.com'

The Django config names match the uppercased DEFAULT keys with a BULK_ELASTIC_SEARCH_LOGGING_ prefix (for example, host → BULK_ELASTIC_SEARCH_LOGGING_HOST).

Tracing

To log activity for critical functions, bes has tracing decorators:

import bes.trace

@bes.trace.trace()
def my_function():
    return 1 + 2 / 3

By default this logs with bes.log using the decorated function’s name (e.g. my_function) as the log type. You can override this if you want something different:

def my_logger(*args, **kwargs):
    print((args, kwargs))

@bes.trace.trace(type='my-type', logger=my_logger)
def my_function():
    return 1 + 2 / 3

Additional trace arguments are passed straight through to the logger:

@bes.trace.trace(index='my-index', type='my-type', sport='triathalon')
def my_function():
    return 1 + 2 / 3

By default, you’ll get separate logged messages before the decorated function starts, after it completes, or if it raises an exception. An action argument is passed to the logger in each case, with values of start, complete, and error respectively. In the error case, the logger is also passed the string-ified exception (error=str(e)) to help with debugging the problem. If you don’t want one or more of these logged messages, you can turn them off:

@bes.trace.trace(start=False, error=False, complete=False):
def my_function():
    return 1 + 2 / 3

although if you turn them all off, you’re not going to get any messages at all ;).

The trace decorator uses wrapt (if it’s installed) to create introspection-preserving decorators. If wrapt is not installed, we fallback to the builtin functools.wraps which handles the basics like docstrings, but doesn’t do as well for more involved introspection (e.g. inspect.getsource).

Testing

Testing uses unittest’s automatic test discovery. Run the test suite with:

$ python -m unittest discover

For Python <3.3, the test suite requires the external mock package, which is bundled as unittest.mock in Python 3.3.