CLF With mod_gzip Extensions

Mod_gzip is another extension to the common log format. It is used by the mod_gzip Apache™ extension which can be used to compress the result of requests before sending them to the client.

mod_gzip is a module developed by RemoteCommunications, Inc. Sourcecode is freely available from http://www.RemoteCommunications.com/apache/mod_gzip/mod_gzip. More informations can be found in their FAQ.

mod_gzip can log information about the compression of pages. To enable this, one can configure Apache™ to log using the 'gzip' format which can be defined as follows:

LogFormat "%h %l %u %t \"%r\" %>s %b %{mod_gzip_result}n \
        %{mod_gzip_compression_ratio}n" gzip
          

This adds two fields at the end of each common log line:

gzip_result compression_ratio

gzip_result

The gzip result code. Usually OK.

compression_ratio

The ratio by which the content was compressed. A number from 0 to 100.