Kohana's built in log is a bit weak , so I rewrite myself.

1) put log module in MODPATH

2) in bootstrap.php

add log to Kohana::modules Kohana::modules(array( 'auth' => MODPATH.'auth', 'cache' => MODPATH.'cache', //... 'log' => MODPATH.'log', ));

then replace origin with this Kohana::$log->attach(new Log_Writer_File(VARPATH.'log')); // this is just for test Kohana::$log->add(Kohana::INFO, 'someone just click the east egg!');

3) edit MODPATH/log/classes/controller/log.php

replace $log_dir to your own log dir;

4) browser http://localhost/path/to/log/day

first it will show exception, because log file is not exists, then add error to log. refresh , it should show the page.