log4js初探

最近由于工作需要，一个nodejs项目，跑在容器云环境上，需要打印日志，初步搜索了下，log4js可以满足需求。

参考资料：

https://www.npmjs.com/package/log4js

以及官网文档

https://log4js-node.github.io/log4js-node/

主要用到的appender是fileAppender.

主要步骤：

1.定义1个log4js的配置文件，log4js.json.

内容如下：

{

"appenders" : {

"access" : {

"type" : "dateFile" ,

"filename" : "log/access.log" ,

"pattern" : "-yyyy-MM-dd" ,

"category" : "http"

},

"app" : {

"type" : "file" ,

"filename" : "log/app.log" ,

"maxLogSize" : 10485760 ,

"numBackups" : 3

},

"errorFile" : {

"type" : "file" ,

"filename" : "log/errors.log"

},

"errors" : {

"type" : "logLevelFilter" ,

"level" : "ERROR" ,

"appender" : "errorFile"

}

},

"categories" : {

"default" : { "appenders" : [ "app" , "errors" ], "level" : "DEBUG" },

"http" : { "appenders" : [ "access" ], "level" : "DEBUG" }

}

}

2.在应用启动时(app.js)加载改配置文件，

var log4js = require ( 'log4js' );

log4js.configure('./config/log4js.json');

var log = log4js . getLogger ( "app" );

app . use (log4js . connectLogger (log4js . getLogger ( "http" ), { level : 'auto' }));

3.在业务js中可以这么用：

var log = require ( 'log4js' ). getLogger ( "index" );

log . debug ( "This is in the index module" );