I'm writting some Perl CGI scripts, and am using Log4perl to log to various files. I thought it may be useful to be able to trace a particular (or various) user's activities to a separate log file. I can put a hook into my session routine to stuff the userid into the MDC, but I don't know of any way to access the MDC from a filter. As far as I know, the MDC is only used for pattern creation.
Is this doable with Log4perl?
Per suggestion below I added a filter in my config file, but it's still not working:
log4perl.appender.User = Log::Log4perl::Appender::File
log4perl.appender.User.filename = /data/wwwwii/logs/appUser.log
log4perl.appender.User.syswrite = 1
log4perl.appender.User.Filter = User
log4perl.appender.User.layout = PatternLayout
log4perl.appender.User.layout.ConversionPattern=%p{1} %d{ISO8601}Z [%03r] %15X{remoteAddr}/%05P %M %L --> %m%n
log4perl.filter.User = sub { Log::Log4perl::MDC->get('userId') == 12; }
I stuff the userid as soon as I do the session lookup, but I never do get an appUser.log file created. No errors show up that I can see.
Can't you just do:
my $value = Log::Log4perl::MDC->get($key); # for 1 value, or
my $hashref = Log::Log4perl::MDC->get_context; # for the whole context