Skip to main content

Zope 3 tracelog implementation for zserver

Project description

***********************
Zope 3/ZServer tracelog
***********************

This package implements a Zope2-style (extended) tracelog. A tracelog
is a kind of access log that records several low-level events for each
request. Each log entry starts with a record type, a request
identifier and the time. Some log records have additional data.

- Request begins:

B -1214390740 2007-04-27T20:16:55 GET /

Includes the request method and path.

- Got request input:

I -1214390740 2007-04-27T20:16:55 0

Includes the request content length.

- Entered application thread:

C -1214390740 2007-04-27T20:16:55

- Application done:

A -1223774356 2007-04-27T20:16:55 500 84

Includes the response content length.

- Request done:

E -1223774356 2007-04-27T20:16:55

In addition, application startup is logged with an 'S' record:

S 0 2007-04-27T20:24:29

To create a trace log, include the zc.zservertracelog package in your
site ZCML configuration. Also, define a logger section in zope.conf::

<logger>
name zc.tracelog
propagate false

<logfile>
format %(message)s
path /home/jim/p/zc.zservertracelog/dev/trace.log
</logfile>

</logger>

where, of course, you'll need to specify a log file path.

The analysis script, tracereport, can be used to analyze the trace
log. I recommend the html output option.





Detailed Documentation
**********************


==================
ZServer TraceLog
==================

A tracelog is a kind of access log that records several low-level events for
each request. Each log entry starts with a record type, a request identifier
and the time. Some log records have additional data.

>>> import zc.zservertracelog.tracelog
>>> import zope.app.appsetup.interfaces

For these examples, we'll add a log handler that outputs to standard out.

>>> import logging
>>> import sys
>>> stdout_handler = logging.StreamHandler(sys.stdout)

>>> logger = logging.getLogger('zc.zservertracelog')
>>> logger.setLevel(logging.INFO)
>>> logger.addHandler(stdout_handler)


Server Startup
==============

There is an event handler to log when the Z server starts.

>>> zc.zservertracelog.tracelog.started(
... zope.app.appsetup.interfaces.ProcessStarting())
S 0 2008-08-26T11:55:00


Tracing Applications
====================

The tracelog machinery is implemented as a WSGI layer, so we'll pass a fake
WSGI application to tracelog for these examples.

>>> faux_app = FauxApplication()

Now, let's create an instance of the tracelog server.

>>> addr, port = '127.0.0.1', 12345

>>> trace_server = zc.zservertracelog.tracelog.Server(
... faux_app, None, addr, port)

Let's also define a convenience function for processing requests.

>>> def invokeRequest(req):
... channel = trace_server.channel_class(trace_server, None, addr)
... channel.received(req)

Process a simple request.

>>> req1 = """\
... GET /test-req1 HTTP/1.1
... Host: www.example.com
...
... """

>>> invokeRequest(req1)
B 23423600 2008-08-27T10:54:08 GET /test-req1
I 23423600 2008-08-27T10:54:08 0
C 23423600 2008-08-27T10:54:08
A 23423600 2008-08-27T10:54:08 200 ?
E 23423600 2008-08-27T10:54:08


Application Errors
==================

The tracelog will also log application errors. To show this, we'll set up
our test application to raise an error when called.

>>> def app_failure(*args, **kwargs):
... raise Exception('oh noes!')
>>> faux_app.app_hook = app_failure

Invoking the request produces log entries for every trace point, and the
application error is written to the *Application End (A)* trace entry.

>>> try:
... invokeRequest(req1)
... except:
... pass
B 21663984 2008-09-02T11:19:26 GET /test-req1
I 21663984 2008-09-02T11:19:26 0
C 21663984 2008-09-02T11:19:26
A 21663984 2008-09-02T11:19:26 Error: oh noes!
E 21663984 2008-09-02T11:19:26


Response Errors
===============

The tracelog also handles errors that can be generated when writing to the
response. To show this, we'll set up our test application to return a
response that produces an error when written to.

>>> def response_of_wrong_type(*args, **kwargs):
... return object()
>>> faux_app.app_hook = response_of_wrong_type

Invoking the request produces log entries for every trace point, and the
error is written to the *Request End (E)* trace entry.

>>> try:
... invokeRequest(req1)
... except:
... pass
B 21651664 2008-09-02T13:59:02 GET /test-req1
I 21651664 2008-09-02T13:59:02 0
C 21651664 2008-09-02T13:59:02
A 21651664 2008-09-02T13:59:02 200 ?
E 21651664 2008-09-02T13:59:02 Error: iteration over non-sequence

Let's clean up before moving on.

>>> faux_app.app_hook = None


Log Messages Containing Line Breaks
===================================

Messages to the tracelog that contain newline characters will not split a log
entry into multiple lines.

>>> req2 = """\
... GET /test-req2/%0Aohnoes/ HTTP/1.1
... Host: www.example.com/linebreak
...
... """

>>> invokeRequest(req2)
B 21598352 2008-09-12T11:40:27 GET /test-req2/\nohnoes/
I 21598352 2008-09-12T11:40:27 0
C 21598352 2008-09-12T11:40:27
A 21598352 2008-09-12T11:40:27 200 ?
E 21598352 2008-09-12T11:40:27


Request Query Strings
=====================

The tracelog preserves request query strings.

>>> req3 = """\
... GET /test-req3/?creature=unicorn HTTP/1.1
... Host: www.example.com/query-string
...
... """

>>> invokeRequest(req3)
B 21598352 2008-09-12T11:40:27 GET /test-req3/?creature=unicorn
I 21598352 2008-09-12T11:40:27 0
C 21598352 2008-09-12T11:40:27
A 21598352 2008-09-12T11:40:27 200 ?
E 21598352 2008-09-12T11:40:27

Empty query strings are also preserved.

>>> req4 = """\
... GET /test-req4/? HTTP/1.1
... Host: www.example.com/empty-query-string
...
... """

>>> invokeRequest(req4)
B 21598352 2008-09-12T11:40:27 GET /test-req4/?
I 21598352 2008-09-12T11:40:27 0
C 21598352 2008-09-12T11:40:27
A 21598352 2008-09-12T11:40:27 200 ?
E 21598352 2008-09-12T11:40:27


Adding Additional Entries to the Trace Log
==========================================

A tracelog object is added to the WSGI environment on each request. This
object implements ``ITraceLog`` and provides applications a method to add
custom entries to the log.

Here is an example application that adds a custom entry to the tracelog.

>>> def noisy_app(environ, start_response):
... logger = environ['zc.zservertracelog.interfaces.ITraceLog']
... logger.log('beep! beep!')
>>> faux_app.app_hook = noisy_app

>>> invokeRequest(req1)
B 21569456 2008-09-12T15:51:05 GET /test-req1
I 21569456 2008-09-12T15:51:05 0
C 21569456 2008-09-12T15:51:05
X 21569456 2008-09-12T15:51:05 beep! beep!
A 21569456 2008-09-12T15:51:05 200 ?
E 21569456 2008-09-12T15:51:05


=========
Changes
=========

0.4 (2008-10-09)
----------------

- added automated tests.

- fixed bug where log entries could be split by messages containing newline
characters.

- added request query strings to log.

- added the tracelog to the WSGI environment.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for zc.zservertracelog, version 1.0.0
Filename, size File type Python version Upload date Hashes
Filename, size zc.zservertracelog-1.0.0.tar.gz (13.3 kB) File type Source Python version None Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page