Question: How is logging handled in Craft 3? There's nothing mentioned in [the docs](https://github.com/craftcms/docs) at all.

None of the below exist.

* Craft::log()
* MyPlugin::log()
* MyPlugin::$plugin->log()

I'm not seeing any logging in any of the other plugins I've got on this site.

Halp!

Answer: 
You can use `Craft::getLogger()->log($message, $level, $category = 'application')`

It uses the [Yii2 logger](http://www.yiiframework.com/doc-2.0/yii-log-logger.html), you can change the `$category` to your plugin handle

Edit: You can use the "short" syntax as well [class reference](https://docs.craftcms.com/api/v3/craft.html)

```
Craft::warning($message, $category);

```

or 

```
Craft::info($message, $category);

```
Another perhaps simpler approach is to write to your own log file without using the Craft logger at all.

```
$file = Craft::getAlias('@storage/logs/pluginhandle.log');
$log = date('Y-m-d H:i:s').' '.$message."\n";

\craft\helpers\FileHelper::writeToFile($file, $log, ['append' => true]);

```

UPDATE: 

I released the [Log To File Helper](https://github.com/putyourlightson/craft-log-to-file) which provides a simple way for logging messages to a specific file and is intended to be used a helper class for modules and plugins.