16: Collecting Application Info With Logging¶
Capture debugging and error output from your web applications using standard Python logging.
Background¶
It's important to know what is going on inside our web application. In development we might need to collect some output. In production, we might need to detect problems when other people use the site. We need logging.
Fortunately Pyramid uses the normal Python approach to logging. The
scaffold generated, in your development.ini
, has a number of lines that
configure the logging for you to some reasonable defaults. You then see
messages sent by Pyramid (for example, when a new request comes in.)
Objectives¶
- Inspect the configuration setup used for logging
- Add logging statements to your view code
Steps¶
First we copy the results of the
view_classes
step:$ cd ..; cp -r view_classes logging; cd logging $ $VENV/bin/python setup.py develop
Extend
logging/tutorial/views.py
to log a message:1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
import logging log = logging.getLogger(__name__) from pyramid.view import ( view_config, view_defaults ) @view_defaults(renderer='home.pt') class TutorialViews: def __init__(self, request): self.request = request @view_config(route_name='home') def home(self): log.debug('In home view') return {'name': 'Home View'} @view_config(route_name='hello') def hello(self): log.debug('In hello view') return {'name': 'Hello View'}
Make sure the tests still pass:
$ $VENV/bin/nosetests tutorial
Run your Pyramid application with:
$ $VENV/bin/pserve development.ini --reload
Open http://localhost:6543/ and http://localhost:6543/howdy in your browser. Note, both in the console and in the debug toolbar, the message that you logged.
Analysis¶
Our development.ini
configuration file wires up Python standard
logging for our Pyramid application:
[app:main]
use = egg:tutorial
pyramid.reload_templates = true
pyramid.includes =
pyramid_debugtoolbar
[server:main]
use = egg:pyramid#wsgiref
host = 0.0.0.0
port = 6543
# Begin logging configuration
[loggers]
keys = root, tutorial
[logger_tutorial]
level = DEBUG
handlers =
qualname = tutorial
[handlers]
keys = console
[formatters]
keys = generic
[logger_root]
level = INFO
handlers = console
[handler_console]
class = StreamHandler
args = (sys.stderr,)
level = NOTSET
formatter = generic
[formatter_generic]
format = %(asctime)s %(levelname)-5.5s [%(name)s][%(threadName)s] %(message)s
# End logging configuration
In this, our tutorial
Python package is setup as a logger
and configured to log messages at a DEBUG
or higher level. When you
visit http://localhost:6543 your console will now show:
2013-08-09 10:42:42,968 DEBUG [tutorial.views][MainThread] In home view
Also, if you have configured your Pyramid application to use the
pyramid_debugtoolbar
, logging statements appear in one of its menus.
See also
See also Logging.