Log4j 是一个使用 Java 语言编写的，可靠、快速、灵活的日志框架（API），使用 Apache Software License 授权。它被移植到 C、C++、C#、Perl、Python、Ruby 和 Eiffel 语言中。

Log4j 是高度可配置的，在运行期使用外部的配置文件对其进行配置。它按照优先级别记录日志，并可将日志信息定向输出到各种介质，比如数据库、文件、控制台、Unix Syslog等。

Log4j 主要由三部分组成：

确认版本

 "dependencies": {
 "body-parser": "1.18.3",
 "compression": "1.7.2",
 "cookie-parser": "1.4.3",
 "ejs": "2.6.1",
 "express": "4.16.3",
 "forever": "0.15.3",
 "http-proxy-middleware": "0.18.0",
 "log4js": "2.9.0",
 "log4js-logstash-tcp": "1.0.1",
 "serve-favicon": "2.5.0"
 },

Logstash配置

在我向logstash写日志之前，已经有同事向Logstash写过日志了。当时只是知道logstash的ip和端口，没有搞清楚协议，所以没有写进去。

logger

// filename: /logs/logger.js

var log4js = require('log4js')

// 获取配置文件中logstash的IP地址和端口
var {logHost, logPort} = require('../config/index.js') 

if (!logHost || !logPort) {
 console.log('ERROR not config logstash_host or logstash_port')
}

log4js.configure({
 appenders: {
 console: { type: 'console' },
 logstash: {
 // 因为我们的logstash暴露的是tcp写日志的端口，所以我用了log4js-logstash-tcp，
 // 这个需要安装 https://github.com/Aigent/log4js-logstash-tcp
 // 如果你的logstash使用UDP的，参考 https://github.com/log4js-node/logstashUDP
 type: 'log4js-logstash-tcp', 
 host: logHost,
 port: parseInt(logPort)
 }
 },
 categories: {
 default: { appenders: ['logstash'], level: 'debug' }
 }
})

const logger = log4js.getLogger('default')

app.js

// filename: /app.js
var express = require('express')
var compression = require('compression')
var path = require('path')
var log4js = require('log4js')
var proxyMiddleware = require('http-proxy-middleware')
var cookieParser = require('cookie-parser')

var logger = require('./logs/logger.js') // 这了引用了上面的logger
var {proxyTable, maxAge} = require('./config/index.js')

...
Object.keys(proxyTable).forEach(function (context) {
 if (!proxyTable[context].ws) {
 // 这里我是用的反向代理，当代理响应时，开始写日志
 proxyTable[context].onProxyRes = writeLog
 }
 app.use(proxyMiddleware(context, proxyTable[context]))
})
...

// 主要谢日日志的就是这里
function writeLog (proxyRes, req, res) {
 var baseLog = `${req.method} ${proxyRes.statusCode} ${req.cookies.email} ${req.url}`
 var msgObj = {
 method: req.method,
 statusCode: proxyRes.statusCode,
 url: req.url,
 email: req.cookies.email || '',
 sessionId: req.cookies.sessionId || '',
 instanceId: 'newTm',
 nodeName: 'newTm'
 }

 if (proxyRes.statusCode < 400) {
 logger.info(baseLog, msgObj)
 } else {
 logger.error(baseLog, msgObj)
 }
}

在kibana中输入关键词：nodeName:newTm


可以搜到如下的记录

{
 "_index": "logstash-2018.07.11",
 "_type": "logs",
 "_id": "AWSIGyY0vR6RLdfU8xZj",
 "_score": null,
 "_source": {
 "nodeName": "newTm",
 "method": "GET",
 "level": "INFO",
 "sessionId": "",
 "message": "GET 204 test.cc.com /api/touch?_=1531291286527",
 "url": "/api/touch?_=1531291286527",
 "@timestamp": "2018-07-11T06:53:29.059Z",
 "port": 57250,
 "@version": "1",
 "host": "192.168.2.74",
 "fields": {
 "nodeName": "newTm",
 "method": "GET",
 "level": "INFO",
 "sessionId": "",
 "category": "default",
 "url": "/api/touch?_=1531291286527",
 "email": "test.cc.com",
 "statusCode": 204
 },
 "category": "default",
 "email": "test.cc.com",
 "statusCode": 204
 },
 "fields": {
 "@timestamp": [
 1531292009059
 ]
 },
 "highlight": {
 "nodeName": [
 "@kibana-highlighted-field@newTm@/kibana-highlighted-field@"
 ]
 },
 "sort": [
 1531292009059
 ]
}

注意