1 return [
 2     ‘traceLevel‘ => YII_DEBUG ? 3 : 0,
 3     ‘targets‘ => [     //可以配置多个log 
 4         [
 5             ‘class‘ => ‘yii\log\FileTarget‘,  //Yii2处理日志的类
 6             ‘levels‘ => [‘error‘, ‘warning‘, ‘info‘], //设置日志记录的级别
 7             ‘categories‘ => [‘user‘], //自定义日志分类
 8             ‘maxFileSize‘ => 1024 * 20,  //设置文件大小，以k为单位
 9             ‘logFile‘ => ‘@runtime/../logs/user‘.date(‘Ymd‘), //自定义文件路径 (一般项目的日志会打到服务器的其他路径，需要修改相应目录的权限哦~)
10             ‘logVars‘ => [‘_POST‘],  //捕获请求参数
11             ‘fileMode‘ => 0775, //设置日志文件权限
12             ‘maxLogFiles‘ => 100,  //同个文件名最大数量
13             ‘rotateByCopy‘ => false, //是否以复制的方式rotate
14             ‘prefix‘ => function() {   //日志格式自定义 回调方法
15                 if (Yii::$app === null) {
16                     return ‘‘;
17                 }
18                 $request = Yii::$app->getRequest();
19                 $ip = $request instanceof Request ? $request->getUserIP() : ‘-‘;
20                 $controller = Yii::$app->controller->id;
21                 $action = Yii::$app->controller->action->id;
22                 return "[$ip][$controller-$action]";
23             },
24         ],
25 ];

 1 class FileTarget extends Target
 2 {
 3     public $logFile;
 4     //rotation开关  如果开启，当日志文件大于maxFileSize设定的文件大小之后，就会自动切分日志
 5     public $enableRotation = true;    
 6     public $maxFileSize = 10240; // in KB
 7     //同一个文件名可以切分多少个文件
 8     public $maxLogFiles = 5;
 9     public $fileMode; //日志文件权限
10     public $dirMode = 0775; 
11     /**
12      * @var bool Whether to rotate log files by copy and truncate in contrast to rotation by
13      * renaming files. Defaults to `true` to be more compatible with log tailers and is windows
14      * systems which do not play well with rename on open files. Rotation by renaming however is
15      * a bit faster.
16      *
17      * The problem with windows systems where the [rename()](http://www.php.net/manual/en/function.rename.php)
18      * function does not work with files that are opened by some process is described in a
19      * [comment by Martin Pelletier](http://www.php.net/manual/en/function.rename.php#102274) in
20      * the PHP documentation. By setting rotateByCopy to `true` you can work
21      * around this problem.
22      */ 
23     public $rotateByCopy = true;
24 
25     /**
26      * Rotates log files.
27      */
28     protected function rotateFiles()
29     {
30         $file = $this->logFile;
31         for ($i = $this->maxLogFiles; $i >= 0; --$i) {
32             // $i == 0 is the original log file
33             $rotateFile = $file . ($i === 0 ? ‘‘ : ‘.‘ . $i);
34             if (is_file($rotateFile)) {
35                 // suppress errors because it‘s possible multiple processes enter into this section
36                 if ($i === $this->maxLogFiles) {
37                     @unlink($rotateFile);
38                 } else {
39                     if ($this->rotateByCopy) {
40                         @copy($rotateFile, $file . ‘.‘ . ($i + 1));
41                         if ($fp = @fopen($rotateFile, ‘a‘)) {
42                             @ftruncate($fp, 0);
43                             @fclose($fp);
44                         }
45                         if ($this->fileMode !== null) {
46                             @chmod($file . ‘.‘ . ($i + 1), $this->fileMode);
47                         }
48                     } else {
49                         // linux下用rename方式
50                         @rename($rotateFile, $file . ‘.‘ . ($i + 1));
51                     }
52                 }
53             }
54         }
55     }
56 }

 1 public function getMessagePrefix($message)
 2 {
 3     if ($this->prefix !== null) {
 4         return call_user_func($this->prefix, $message);
 5     }
 6 
 7     if (Yii::$app === null) {
 8         return ‘‘;
 9     }
10 
11     $request = Yii::$app->getRequest();
12     $ip = $request instanceof Request ? $request->getUserIP() : ‘-‘;
13 
14     /* @var $user \yii\web\User */
15     $user = Yii::$app->has(‘user‘, true) ? Yii::$app->get(‘user‘) : null;
16     if ($user && ($identity = $user->getIdentity(false))) {
17         $userID = $identity->getId();
18     } else {
19         $userID = ‘-‘;
20     }
21 
22     /* @var $session \yii\web\Session */
23     $session = Yii::$app->has(‘session‘, true) ? Yii::$app->get(‘session‘) : null;
24     $sessionID = $session && $session->getIsActive() ? $session->getId() : ‘-‘;
25 
26     return "[$ip][$userID][$sessionID]";
27 }