Allow logging host name in the access log when using multiple virtual domains

Originally reported by: Anonymous

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If you have a webapp that serves multiple virtual hosts, the distinction which page was served for which host can't be recorded in the logfile, since there is currently no way to have the request.headers['host'] logged in access.log. For that, I made a one line addition to _cplogging.py/access(), in the atoms dict, I added an entry 'o' which allows one to log the Host the request came from.

With the patch, it becomes possible to do this:

log=app.log
log.access_log_format='%(h)s %(l)s %(u)s %(t)s "%(r)s" %(s)s %(b)s "%(f)s" "%(a)s" %(o)s'
# Note the %(o)s at the end, which logs the Host

The patch, against trunk #2689:

--- _cplogging.py.2689  2010-08-21 11:37:19.000000000 +0200
+++ _cplogging.py   2010-08-21 11:37:41.000000000 +0200
@@ -217,6 +217,7 @@
                  'b': dict.get(outheaders, 'Content-Length', '') or "-",
                  'f': dict.get(inheaders, 'Referer', ''),
                  'a': dict.get(inheaders, 'User-Agent', ''),
+                 'o': dict.get(inheaders, 'Host', '-'),
                  }
         for k, v in atoms.items():
             if isinstance(v, unicode):

Reported by motoom@xs4all.nl

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• Bitbucket: https://bitbucket.org/cherrypy/cherrypy/issue/1019

Original comment by Anonymous:

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In that case the log doesn't respect the CLF spec I'm afraid.

http://en.wikipedia.org/wiki/Common_Log_Format

I'd rather vhosts to log each in their own log files.

Original comment by Anonymous:

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Ah, to clarify:

In my application, which serves hundreds to thousands of virtual domains, it will be undesirable to have so much logfiles lying around (and being open and written to simultaneously). I plan to do the log analysis later, based on selective extraction of log lines using the virtualhostname.

Furthermore, I do not propose a change to the logging format, only the ''possibility'' of using the virtual hostname in the log, if someone desires so (this requires explicit redefinition of app.log.access_log_format, if you leave that at the default you'll get a perfectly conforming CLF, even with my patch in place).

Thinking of it, it would be nice if access() could log any field from inheaders or outheaders, not just the pre-canned ones. But that's an exercise for later ;-)

Original comment by Jason R. Coombs (Bitbucket: jaraco, GitHub: jaraco):

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Fixed in 20690b4bd948 (Pull Request #38)