title: CakePHP 3 Custom Logging
body: <p>I am trying to configure a custom log-file but I do not understand the official documentation's examples.</p>
  
  <p>It describes how to use the FileLog Adapter by specifying a stanza like the following and put it into the config/app.php file (however the app.php file is not consistent with this format):</p>
  
  <pre><code>Log::config('custom_path', [
  'className' =&gt; 'File',
  'path' =&gt; '/path/to/custom/place/'
  ]);
  </code></pre>
  
  <p>And then, presumably, to use this stanza in a class file as follows:</p>
  
  <pre><code>$this-&gt;log("Something didn't work!", 'custom_path');
  </code></pre>
  
  <p>But then a message is written to the custom_path file containing the error</p>
  
  <pre><code>Invalid log level "custom_path"
  </code></pre>
  
  <p>Any help appreciated.</p>