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<p>This creates another appender named <code>SCREEN</code>. We then need to tell our root logger to use this appender
as well:</p>
<pre class="prettyprint">log4perl.rootLogger = DEBUG, LOG1, SCREEN</pre>

<p>Now, restart your application, and visit a route that has logging installed, and you will see your log
message not only goes to the <i>logs/mylog.log</i> file, but also displays on the console running your
application. Easy!</p>
<h2><a name="some_gotchas"></a>Some Gotchas</h2>

<p>There are a couple of important nuances you should be aware of:</p>
<ul>
<li><a name="item_Environment_configuration_replaces_logging_configuration"></a><b>Environment configuration replaces logging configuration</b>
<p>If you put your logging configuration in <i>config.yml</i> rather than one of your environment-specific
configuration files (such as <i>environments/development.yml</i>), you stand a good chance of not using
the logging configuration you think you are using. The default configuration file for the development
environment, for example, logs only to the console. If you put your Log4perl configuration in <i>config.yml</i>
and don't change your development configuration file, your Log4perl configuration will be passed over
for the default console logger.</p>
<p>From my own experience, <b>always</b> configure your logger in your environment-specific configuration, unless
you use the same configuration across all environments (I don't endorse this practice).</p>
</li>
<li><a name="item_Core_level_messages_are_passed_as_log_level_trace__but_will_not_be_passed_unless_Dancer2_s_log_level_is_core_"></a><b>Core level messages are passed as log level trace, but will not be passed unless Dancer2's log level is core.</b>
<p>Since <code>core</code> doesn't have a good corresponding level in Log4perl, <code>core</code> level messages are sent 
over to Log4perl at the <code>trace</code> log level. This <b>only</b> happens when you set Dancer2's log level in your
<i>config.yml</i> file to <code>core</code> however. So your preferred log level setting is respected, even if <code>core</code> level 
messages have to be reported at a different level.</p>
</li>
<li><a name="item__code_log__code__should_be_set_a_lower_priority_than_the_lowest_priority_as_set_in_your_Log4perl_configuration_"></a><b><code>log</code> should be set a lower priority than the lowest priority as set in your Log4perl configuration.<...
<p>If it isn't, the log messages will not be passed to Log4perl.</p>
</li>
</ul>
<h2><a name="conclusion"></a>Conclusion</h2>

<p>If Log4perl is all the logging you need in your Dancer2 applications, then <code>Dancer2::Logger::Log4perl</code> is well worth
a look. It gives you much of the functionality available to Log4perl while using the logging syntax built into Dancer2.
This article should give you sufficient grounding to get going with Log4perl in your Dancer2 applications.</p>
<h2><a name="further_reading"></a>Further Reading</h2>

<ul>
<li><a name="item__a_href__https___metacpan_org_pod_Dancer2__Logger__Log4perl__Dancer2__Logger__Log4perl__a_"></a><b><a href="https://metacpan.org/pod/Dancer2::Logger::Log4perl">Dancer2::Logger::Log4perl</a></b>
</li>
<li><a name="item__a_href__https___metacpan_org_pod_Log__Log4perl__Log4perl__a_"></a><b><a href="https://metacpan.org/pod/Log::Log4perl">Log4perl</a></b>
</li>
<li><a name="item__a_href__https___www_perl_com_pub_2002_09_11_log4perl_html___Log4Perl_Tutorial__a_"></a><b><a href="https://www.perl.com/pub/2002/09/11/log4perl.html/">Log4Perl Tutorial</a></b>
</li>
</ul>
<h2><a name="author"></a>Author</h2>

<p>This article has been written by Jason Crome (CromeDome) for the Perl Dancer 
Advent Calendar 2018.</p>
<h2><a name="copyright"></a>Copyright</h2>

<p>No copyright retained. Enjoy.</p>
<p>Jason A. Crome</p>
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