Apache Module mod_log_debug

Examples

1. Log message after request to /foo/* is processed:

   <Location "/foo/">
   LogMessage "/foo/ has been requested"
   </Location>

2. Log message if request to /foo/* is processed in a sub-request:

   <Location "/foo/">
   LogMessage "subrequest to /foo/" hook=type_checker expr=%{IS_SUBREQ}
   </Location>

   The default log_transaction hook is not executed for sub-requests, therefore we have to use a different hook.
3. Log message if an IPv6 client causes a request timeout:

   LogMessage "IPv6 timeout from %{REMOTE_ADDR}" "expr=-T %{IPV6} && %{REQUEST_STATUS} = 408"

   Note the placing of the double quotes for the expr= argument.
4. Log the value of the "X-Foo" request environment variable in each stage of the request:

   <Location "/">
   LogMessage "%{reqenv:X-Foo}" hook=all
   </Location>

   Together with microsecond time stamps in the error log, hook=all also lets you determine the times spent in the different parts of the request processing.

LogMessage message [hook=hook] [expr=expression]