++ed by:

3 PAUSE users
2 non-PAUSE users.

Breno G. de Oliveira


MojoX::Log::Log4perl - Log::Log4perl logging for Mojo/Mojolicious


In lib/MyApp.pm:

  use MojoX::Log::Log4perl;

  # just create a custom logger object for Mojo/Mojolicious to use
  # (this is usually done inside the "startup" sub on Mojolicious).
  # If we dont supply any arguments to new, it will work almost
  # like the default Mojo logger.
  $self->log( MojoX::Log::Log4perl->new() );

  # But the real power of Log4perl lies in the configuration, so
  # lets try that. example.conf is included in the distribution.
  $self->log( MojoX::Log::Log4perl->new('example.conf') );

  # you can even make it periodically check for changes in the
  # configuration file and automatically reload them while your
  # app is still running!

  # check for changes every 10 seconds
  $self->log( MojoX::Log::Log4perl->new('example.conf', 10)    );

  # or check for changes only upon receiving SIGHUP
  $self->log( MojoX::Log::Log4perl->new('example.conf', 'HUP') );

And later, inside any Mojo/Mojolicious module...

  $c->app->log->debug("This is using log4perl!");


This module provides a Mojo::Log implementation that uses Log::Log4perl as the underlying log mechanism. It provides all the methods listed in Mojo::Log (and many more from Log4perl - see below), so, if you already use Mojo::Log in your application, there is no need to change a single line of code!

There will be a logger component set for the package that called it. For example, if you were in the MyApp::Main package, the following:

  package MyApp::Main;
  use base 'Mojolicious::Controller';
  sub default {
      my ( $self, $c ) = @_;
      my $logger = $c->app->log;

Would send a message to the Myapp.Main Log4perl component. This allows you to seamlessly use Log4perl with Mojo/Mojolicious applications, being able to setup everything from the configuration file. For example, in this case, we could have the following log4perl.conf file:

  # setup default log level and appender
  log4perl.rootLogger = DEBUG, FOO
  log4perl.appender.FOO = Log::Log4perl::Appender::File

  # setup so MyApp::Main only logs fatal errors
  log4perl.logger.MyApp.Main = FATAL

See Log::Log4perl and Log::Log4perl::Config for more information on how to configure different logging mechanisms based on the component.




This builds a new MojoX::Log::Log4perl object. If you provide an argument to new(), it will be passed directly to Log::Log4perl::init.

What you usually do is pass a file name with your Log4perl configuration. But you can also pass a hash reference with keys and values set as Log4perl configuration elements (i.e. left side of '=' vs. right side).

If you don't give it any arguments, the following default configuration is set:

  log4perl.rootLogger = DEBUG, SCREEN
  log4perl.appender.SCREEN = Log::Log4perl::Appender::Screen
  log4perl.appender.SCREEN.layout = PatternLayout
  log4perl.appender.SCREEN.layout.ConversionPattern = [%d] [mojo] [%p] %m%n

new( $config, $delay )

As an optional second argument to new(), you can set a delay in seconds that will be passed directly to Log::Log4perl::init_and_watch. This makes Log4perl check every $delay seconds for changes in the configuration file, and reload it if the file modification time is different.

You can also define a signal to watch and Log4perl will setup a signal handler to check the configuration file again only when that particular signal is received by the application, for example via the kill command:

  kill -HUP pid


  $logger->warn("something's wrong");

Below are all log levels from MojoX::Log::Log4perl, in descending priority:







Just like Log::Log4perl: "If your configured logging level is WARN, then messages logged with info(), debug(), and trace() will be suppressed. fatal(), error() and warn() will make their way through, because their priority is higher or equal than the configured setting."

The return value is the log object itself, to allow method chaining and further manipulation.


You can also use the log() method just like in Mojo::Log:

  $logger->log( info => 'I can haz cheezburger');

But nobody does that, really.

As with the regular logging methods, the return value is the log object itself.


  if ($logger->is_debug) {
      # expensive debug here

As usual, you can (and should) avoid doing expensive log calls by checking the current log level:








You can also use the is_level() method just like in Mojo::Log:

  $logger->is_level( 'warn' );

But nobody does that, really.


The following log4perl methods are also available for direct usage:



This will behave just like:

       && warn $message;



This will behave just like:

       && die $message;

If you also wish to use the ERROR log level with warn() and die(), you can:



This will behave just like:

       && warn $message;



This will behave just like:

       && die $message;

Finally, there's the Carp functions that do just what the Carp functions do, but with logging:


    $logger->logcarp();        # warn w/ 1-level stack trace


    $logger->logcluck();       # warn w/ full stack trace


    $logger->logcroak();       # die w/ 1-level stack trace


    $logger->logconfess();     # die w/ full stack trace


Differences from Mojo::Log

The original handle and path attributes from Mojo::Log are not implemented as they make little sense in a Log4perl environment, and will trigger a warning if you try to use them.

The format attribute is also not implemented, and will trigger a warning when used. For compatibility with Mojolicious' current 404 development page, this attribute will work returning a basic formatted message as "[ date ] [ level ] message". We do not recommend you to rely on this as we may remove it in the future. Please use Log4perl's layout formatters instead.

The following attributes are still available:


  my $level = $logger->level();

This will return an UPPERCASED string with the current log level ('DEBUG', 'INFO', ...).

Note: You can also use this to force a level of your choosing:

  $logger->level('warn');  # forces 'warn' level (case-insensitive)

But you really shouldn't do that at all, as it breaks log4perl's configuration structure. The whole point of Log4perl is letting you setup your logging from outside your code. So, once again: don't do this.


This returns the last few logged messages as an array reference in the format:

        [ 'timestamp', 'level', 'message' ], # older first
        [ 'timestamp', 'level', 'message' ],


Maximum number of messages to be kept in the history buffer (see above). Defaults to 10.


Breno G. de Oliveira, <garu at cpan.org>


Please report any bugs or feature requests to bug-mojo-log-log4perl at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MojoX-Log-Log4perl. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.


You can find documentation for this module with the perldoc command.

    perldoc MojoX::Log::Log4perl

You can also look for information at:


This module was heavily inspired by Catalyst::Log::Log4perl. A lot of the documentation and specifications were taken almost verbatim from it.

Also, this is just a minor work. Credit is really due to Michael Schilli and Sebastian Riedel, creators and maintainers of Log::Log4perl and Mojo, respectively.


Log::Log4perl, Mojo::Log, Mojo, Mojolicious


Copyright 2009-2016 Breno G. de Oliveira, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.