WSGI middleware for statsd timing
wsgi_statsd is a WSGI middleware that provides an easy way to time all requests. Integration is as easy as just wrapping your existing wsgi application.
In your wsgi.py file wrap your WSGI application as follows:
import statsd from wsgi_statsd import StatsdTimingMiddleware def application(environ, start_response): response_body = 'The request method was %s' % environ['REQUEST_METHOD'] status = '200 OK' response_headers = [('Content-Type', 'text/plain'), ('Content-Length', str(len(response_body)))] start_response(status, response_headers) return [response_body] client = statsd.StatsClient( prefix='your_prefix', host='your_host', port=8125 ) application = StatsdTimingMiddleware(application, client)
If an unhandled exception happens, it will not be timed by default. This is a design decision to separate error reporting and actual statistical measurements. To enable exception timing, pass time_exception=True to the middleware constructor:
application = StatsdTimingMiddleware(application, client, time_exceptions=True)
wsgi-statsd uses the statsd timer function, generates a key and sets the amount of time the request took as the value. The key is constructed as follows:
Using the foo prefix, in your statsd client, and calling the www.spam.com/bar/test/ page will result in foo .bar_test.GET.200 having a value equal to the time it took to handle the request.
If you passed time_exceptions=True and any exception occurs during the response, then the key name will be postfixed with the exception class name: foo.bar_test.GET.500.ValueError.
It’s possible to customize the way wsgi_statsd generates the key and/or time. StatsdTimingMiddleware has send_stats and get_key_name which you can override:
class CustomStatsdMiddleware(StatsdTimingMiddleware): def get_key_name(self, environ, response_interception): return super(self, CustomStatsdMiddleware).get_key_name(environ, response_interception) + '.' + environ['Transfer-Encoding'] def send_stats(self, start, environ, response_interception): super(self, CustomStatsdMiddleware).send_stats(start + 10, environ, response_interception)
wsgi-statsd uses underscores as a separator for the path part of the key that is sent to statsd as that makes it easy to retrieve the data from graphite. You can override this default by passing a separator value to the middleware constructor:
StatsdTimingMiddleware(application, client, separator='.')
If you have questions, bug reports, suggestions, etc. please create an issue on the GitHub project page.
- Added clean target to Makefile.
- Added the changes for the 0.2.6 version.
- Updated documentation.
- Fixed issue with the separator parameter. It now functions as expected and documented.
- Add separator parameter to StatsdTimingMiddleware.__init__().
- Add exception class name to the key when exception happens (bubenkoff)
- ensure close() is properly called from the response (bubenkoff, GrahamDumpleton)
- optionally time exceptions (bubenkoff)
- code readability improvements (bubenkoff)
- Fixed version numbers
- Added support for WSGI applications returning generators
- Added a test to verify that the response body remains the same after passing through the middleware
- Initial public release